Patent Publication Number: US-8970339-B2

Title: Integrated magnetic assemblies and methods of assembling same

Description:
BACKGROUND 
     The field of the embodiments relate generally to power electronics, and more particularly, to integrated magnetic assemblies for use in power electronics. 
     High density power electronic circuits often require the use of multiple magnetic electrical components for a variety of purposes, including energy storage, signal isolation, signal filtering, energy transfer, and power splitting. As the demand for higher power density electrical components increases, it becomes more desirable to integrate two or more magnetic electrical components, such as multiple inductors, into the same core or structure. 
     However, known integrated magnetic assemblies are sometimes not adequately configured to permit multiple windings to be manufactured on a single structure and operate independently of one another. As a result, separate cores or structures are used when multiple components are operated independently in a given electronics circuit, thereby increasing the number and size of the components needed for a given operation, and reducing the power density of a given electronics circuit. 
     Other known integrated magnetic assemblies do not permit flexibility in the positioning of the input and output portions of the windings used in such assemblies. Still other known integrated magnetic assemblies require a relatively complex and/or costly fabrication process. 
     BRIEF DESCRIPTION 
     In one aspect, 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. 
     In another aspect, an integrated magnetic assembly is provided. The integrated magnetic assembly includes a magnetic core, a first winding, and a second winding. The magnetic core 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. The second U-core has a relatively high magnetic permeability, and includes a second surface. 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. The first winding includes a first section recessed within the first surface, and is inductively coupled to the first U-core. The second winding includes a second section recessed within the second surface, and is inductively coupled to the second U-core. 
     In yet another aspect, a method of assembling an integrated magnetic assembly is described. The method includes providing a magnetic base within a magnetic core, the magnetic base including a first U-core having a relatively high magnetic permeability, a second U-core having a relatively high magnetic permeability, and a spacing member, the first U-core including a first surface and the second U-core including a second surface, providing a magnetic plate within the magnetic core, connecting the spacing member to the first U-core and the second U-core such that the first and second surfaces are substantially coplanar and a gap having a relatively low magnetic permeability is formed between the first and second U-cores, and coupling the magnetic plate to the magnetic base such that the magnetic plate substantially covers the first and second surfaces. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of an exemplary integrated magnetic assembly including a magnetic core. 
         FIG. 2  is a top view of the magnetic core shown in  FIG. 1  with certain features removed for illustration. 
         FIG. 3  is a side view of the magnetic core shown in  FIG. 1  with certain features removed for illustration. 
         FIG. 4  is a plot of inductance versus current in an inductive winding assembly in the integrated magnetic assembly shown in  FIG. 1 . 
         FIG. 5  is an exploded view of an alternative integrated magnetic assembly, including a magnetic base. 
         FIG. 6  is a top view of the magnetic base shown in  FIG. 5 . 
         FIG. 7  is a side view of the magnetic base shown in  FIG. 5 . 
         FIG. 8  is a plot of inductance versus current in an inductive winding assembly in the integrated magnetic assembly shown in  FIG. 5 . 
         FIG. 9  is an exploded view of an alternative integrated magnetic assembly. 
         FIG. 10  is a flowchart of an exemplary method for assembling an integrated magnetic assembly. 
     
    
    
     Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     DETAILED DESCRIPTION 
     Exemplary embodiments of integrated magnetic assemblies are described herein. A 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. 
     The embodiments described herein include cost effective integrated magnetic assemblies having multiple windings capable of operating independently of one another.  FIG. 1  is an exploded view of an exemplary integrated magnetic assembly  100 . In the exemplary embodiment, integrated magnetic assembly  100  includes a magnetic core  102 , a first winding  104  inductively coupled to magnetic core  102 , a second winding  106  inductively coupled to magnetic core  102 , and a buffering layer  108 . 
     Magnetic core  102  includes a magnetic base  110  and a magnetic plate  112  coupled to magnetic base  110 . Magnetic base  110  includes a first U-core  114  and a second U-core  116  each having a relatively high magnetic permeability, such as between about 1,500 to 10,000 microhenrys per meter, and a spacing member  118  connecting first and second U-cores  114  and  116  such that a gap  120  (also shown in  FIGS. 2 and 3 ) of relatively low magnetic permeability, such as between about 40 and 500 microhenrys per meter, is formed between first and second U-cores  114  and  116 . In alternative embodiments, either or both of first U-core  114  and second U-core  116  may have a relatively low magnetic permeability, such as between about 40 to 500 microhenrys per meter. 
     First U-core  114  includes a first surface  122  having a first winding channel  124  defined therein, giving first U-core  114  the appearance of a “U” shape when viewed from the side, as shown in  FIG. 3 . First winding channel  124  is configured to receive and inductively couple a conductive winding, such as first winding  104 , to first U-core  114 . First winding channel  124  is partially defined by winding channel sidewalls  126  and  128  that are substantially parallel with each other along the length of first winding channel  124 . 
     In the exemplary embodiment, first winding channel  124  is bent at an angle α (shown in  FIG. 2 ) of about 90 degrees. In alternative embodiments, the angle α at which first winding channel  124  is bent may be any angle that enables the integrated magnetic assembly  100  to function as described herein, such as between about 60 degrees and about 120 degrees, between about 30 degrees and about 150 degrees, or even between about zero degrees and about 180 degrees. In the exemplary embodiment, first winding channel  124  includes a single bend. In alternative embodiments, winding channel may include any number of bends that enables integrated magnetic assembly  100  to function as described herein. Advantageously, the potential inductance of first U-core  114  can be varied by increasing the length of first winding channel  124  along first surface  122  of first U-core  114 . For example, the length of first winding channel  124  may be increased or decreased by adjusting either or both of the angle α at which first winding channel  124  is bent and the number of bends in first winding channel  124 . 
     First U-core  114  also includes a plurality of outer surfaces  130 ,  132 ,  134 , and  136  adjoining first surface  122 , including a front outer surface  130  and a side outer surface  132 . In the exemplary embodiment front outer surface  130  and side outer surface  132  are adjoining surfaces. One or more outer surfaces  130 ,  132 ,  134 , and  136  may have one or more winding channels defined therein. In the exemplary embodiment, front outer surface  130  includes a first terminal winding channel  138  defined therein and connected to first winding channel  124 . Side outer surface  132  includes a second terminal winding channel  140  defined therein and connected to first winding channel  124 . First terminal winding channel  138  extends in a direction substantially perpendicular to first surface  122 . Second terminal winding channel  140  also extends in a direction substantially perpendicular to first surface  122 . Second terminal winding channel  140  also extends between first and second U-cores  114  and  116 . 
     Second U-core  116  similarly includes a second surface  142  having a second winding channel  144  defined therein. In the exemplary embodiment, second surface  142  of second U-core  116  is substantially coplanar with first surface  122  of first U-core  114 . In alternative embodiments, second surface  142  of second U-core  116  may be disposed in a different plane than first surface  122  of first U-core  114 . Second winding channel  144  is configured to receive and inductively couple a conductive winding, such as second winding  106 , to second U-core  116 . Second winding channel  144  is partially defined by winding channel sidewalls  146  and  148  that are substantially parallel with each other along the length of second winding channel  144 . 
     In the exemplary embodiment, second winding channel  144  is bent at an angle β (shown in  FIG. 2 ) of about 90 degrees. In alternative embodiments, the angle β at which second winding channel  144  is bent may be any angle that enables the integrated magnetic assembly  100  to function as described herein, such as between about 60 degrees and about 120 degrees, between about 30 degrees and about 150 degrees, or even between about zero degrees and about 180 degrees. In the exemplary embodiment, second winding channel  144  includes a single bend. In alternative embodiments, winding channel may include any number of bends that enables integrated magnetic assembly  100  to function as described herein. Advantageously, the potential inductance of second U-core  116  can be varied by increasing or decreasing the length of second winding channel  144  along second surface  142  of second U-core  116 . For example, the length of second winding channel  144  may be increased or decreased by adjusting either or both of the angle  3  at which second winding channel  144  is bent and the number of bends in second winding channel  144 . 
     Second U-core  116  also includes a plurality of outer surfaces  150 ,  152 ,  154 , and  156  adjoining second surface  142 , including a front outer surface  150  and a side outer surface  152 . In the exemplary embodiment front outer surface  150  and side outer surface  152  are adjoining surfaces. One or more outer surfaces  150 ,  152 ,  154 , and  156  may have one or more winding channels defined therein. In the exemplary embodiment, front outer surface  150  includes a third terminal winding channel  158  defined therein and connected to second winding channel  144 . Side outer surface  152  includes a fourth terminal winding channel  160  defined therein and connected to second winding channel  144 . Third terminal winding channel  158  extends in a direction substantially perpendicular to second surface  142 . Fourth terminal winding channel  160  also extends in a direction substantially perpendicular to second surface  142 . 
     In the exemplary embodiment, first and second winding channels  124  and  144  defined within first and second U-cores  114  and  116  have substantially the same configuration (i.e., a single bend of about 90 degrees). In alternative embodiments, first and second winding channels  124  and  144  may have different configurations from one another, for example, by having bends with different angles, by having a different number of bends, or both. In yet further alternative embodiments, the inductive winding assemblies formed within first and second U-cores  114  and  116  may have different operational characteristics from one another, such as different inductances, different DC currents, and different operating frequencies. 
     In the exemplary embodiment, first and second U-cores  114  and  116  have generally square cross-sections. In alternative embodiments, first or second U-cores  114  and  116  may have a rectangular, circular, elliptical, or polygonal cross-section. In yet further embodiments, first or second U-cores  114  and  116  may have any other shaped cross-section that enables integrated magnetic assembly  100  to function as described herein. 
     First and second U-cores  114  and  116  are connected by spacing member  118  disposed between first and second U-cores  114  and  116 . Spacing member  118  is connected to first and second U-cores  114  and  116  such that a gap  120  (also shown in  FIGS. 2 and 3 ) of relatively low magnetic permeability is formed between first and second U-cores  114  and  116 . In the exemplary embodiment, spacing member  118  includes a first section  162  and a second section  164  disposed at opposite ends of gap  120  between first and second U-cores  114  and  116 . In this configuration, spacing member  118  acts as a magnetic flux bridge between first U-core  114  and second U-core  116 , providing a continuous magnetic flux path through magnetic core  102  for orthogonal flux (i.e., magnetic flux generated by a winding that is orthogonal to the primary flux path within magnetic core  102 ) produced by a winding inductively coupled to first U-core  114 . In alternative embodiments, first U-core  114 , second U-core  116 , and spacing member  118  may be configured such that spacing member  118  acts as a magnetic flux bridge for orthogonal flux produced by a winding inductively coupled to second U-core  116 . Providing a continuous magnetic flux path through magnetic core  102  for orthogonal flux produced by a winding inductively coupled to first U-core  114  increases the inductance of the winding assembly formed within first U-core  114  at low currents. 
     In the exemplary embodiment, spacing member  118  is constructed of the same material as first and second U-cores  114  and  116  (i.e., ferrite). In alternative embodiments, spacing member  118  may be constructed from a material having a relatively low magnetic permeability, and first and second U-cores  114  and  116  may be constructed of a material having a relatively high magnetic permeability. In yet further alternative embodiments, spacing member  118  may be constructed from a material having a relatively high magnetic permeability, and first and second U-cores  114  and  116  may be constructed of a material having a relatively low magnetic permeability. In yet further alternative embodiments, the size and/or shape of spacing member  118 , including first and second sections  162  and  164 , may be any suitable size and/or shape that enables integrated magnetic assembly  100  to operate as described herein. In yet further alternative embodiments, the location(s) at which spacing member  118  connects first and second U-cores  114  and  116  may be any location(s) between first and second U-cores  114  and  116  that enables integrated magnetic assembly  100  to function as described herein. 
     In the exemplary embodiment, magnetic base  110  is machined from a single piece of magnetic material, such as ferrite. First U-core  114 , second U-core  116 , and spacing member  118  thus comprise a unitary magnetic base. In alternative embodiments, magnetic base  110  may be formed from ferrite polymer composites, powdered iron, sendust, laminated cores, tape wound cores, silicon steel, nickel-iron (e.g., MuMETAL®), amorphous metals, or any other suitable material that enables integrated magnetic assembly  100  to function as described herein. In yet further alternative embodiments, first U-core  114 , second U-core  116 , and/or spacing member  118  may be joined together from multiple pieces that are fabricated separately from the same materials or from different materials. 
     Magnetic plate  112  is coupled to magnetic base  110  such that magnetic plate  112  substantially covers first and second surfaces  122  and  142 . Magnetic plate  112  thereby provides a continuous magnetic flux path through magnetic core  102  for first and second U-cores  114  and  116 . In the exemplary embodiment, magnetic plate  112  comprises a generally solid rectangular plate. In alternative embodiments, magnetic plate  112  may have a generally square, circular, elliptical, or polygonal shape. In yet further embodiments, magnetic plate  112  may have any other shape that enables integrated magnetic assembly  100  to function as described herein. In yet further alternative embodiments, magnetic plate  112  may have one or more holes, notches, voids or gaps defined therein. In the exemplary embodiment, magnetic plate  112  is machined from a single piece of magnetic material, such as ferrite. In alternative embodiments, magnetic base  112  may be formed from ferrite polymer composites, powdered iron, sendust, laminated cores, tape wound cores, silicon steel, nickel-iron (e.g., MuMETAL®), amorphous metals, molded and extruded magnetic materials, such as magnetic foils or magnetic shielding tape, or any other suitable material that enables integrated magnetic assembly  100  to function as described herein. In alternative embodiments, magnetic plate  112  is formed from multiple pieces that are fabricated separately from the same materials or from different materials 
     First winding  104  is inductively coupled to first U-core  114 . First winding  104  is configured to be received within first winding channel  124 . In the exemplary embodiment, first winding  104  is bent at substantially the same angle as first winding channel  124 . 
     First winding  104  includes a first terminal side  166 , a second terminal side  168 , and an inductive section  170  interposed between first and second terminal sides  166  and  168 . Inductive section  170  of first winding  104  is recessed within first surface  122 . In the exemplary embodiment, first terminal side  166  is recessed within front outer surface  130 , and second terminal side  168  is recessed within side outer surface  132 . In alternative embodiments, first and second terminal sides  166  may both be recessed within the same surface, such as front outer surface  130  or side outer surface  132 . 
     Second winding  106  is inductively coupled to second U-core  116 . Second winding  106  is configured to be received within second winding channel  144 . In the exemplary embodiment, second winding  106  is bent at substantially the same angle as second winding channel  144 . 
     Second winding  106  includes a third terminal side  172 , a fourth terminal side  174 , and an inductive section  176  interposed between third and fourth terminal sides  172  and  174 . Inductive section  176  of second winding  106  is recessed within second surface  142 . In the exemplary embodiment, third terminal side  172  is recessed within front outer surface  150  and fourth terminal side  174  is recessed within side outer surface  152 . In alternative embodiments, third and fourth terminal sides  172  and  174  may both be recessed within the same surface, such as front outer surface  150  or side outer surface  152 . 
     In the exemplary embodiment, second winding  106  has substantially the same configuration and orientation as first winding  104 , although multiple orientations of first winding  104  and/or second winding  106  with respect to each other and with respect to magnetic core  102  are possible. 
     In the exemplary embodiment, first and second windings  104  and  106  are formed from layered conductive sheets, such as copper, although any other suitable conductive material may be used for first or second windings  104  and  106  that enables integrated magnetic assembly  100  to function as described herein. 
     In the exemplary embodiment, buffering layer  108  is a thin, planar layer made of a high-heat resistive material, such as Nomex® or polyimide. In alternative embodiments, buffering layer  108  may be made of any material that enables integrated magnetic assembly  100  to function as described herein. In yet further embodiments, buffering layer  108  may be omitted from integrated magnetic assembly  100 . 
       FIG. 4  is a plot illustrating how the inductance of the first winding assembly (i.e., the winding assembly formed by first U-core  114  and first winding  104 ) of integrated magnetic assembly  100  varies as the current applied to first winding  104  increases for various operating temperatures. In the exemplary embodiment, the inductance of the first winding assembly is between about 0.3 μH and 0.4 μH at currents of between about 2 amps and about 30 amps. At lower currents (e.g., less than about 2 amps), the inductance of the first winding assembly is much higher. For example, at currents of about 0.5 amps, the inductance of the first winding assembly is about 1 μH, or about three to four times higher than the inductance of the first winding assembly at higher currents. In alternative embodiments, the current value at which the inductance of the first winding assembly begins to decrease (about 0.5 amps in the exemplary embodiment) can be varied by adjusting the permeability of the magnetic flux path between first U-core  114  and second U-core  116  formed by spacing member  118 . For example, the magnetic flux path between first U-core and second U-core can be varied by changing the size, shape, position, and/or the magnetic permeability of spacing member  118 . 
       FIG. 5  is an exploded view of an alternative embodiment of an integrated magnetic assembly  500 . Unless specified, integrated magnetic assembly  500  is substantially similar to integrated magnetic assembly  100  (shown in  FIG. 1 ). Magnetic plate  112  and buffering layer  108  are omitted for clarity.  FIGS. 6 and 7  are, respectively, top and front views of magnetic base  510  shown in  FIG. 5 . In integrated magnetic assembly  500 , first U-core  114  and second U-core have substantially the same magnetic permeability. Spacing member  518  is disposed on a single side second terminal winding channel  140 . As a result, no continuous magnetic flux path is formed between first and second U-cores  114  and  116  through which orthogonal flux can flow. As a result, the inductance of the winding assembly formed within first U-core  114  will be substantially the same at lower currents as it is at higher currents when compared to integrated magnetic assembly  100 . Additionally, first and second U-cores  114  and  116  may be operated independently of one another, despite having substantially the same magnetic permeability. 
       FIG. 8  is a plot illustrating how the inductance of the first winding assembly (i.e., the winding assembly formed by first U-core  114  and first winding  104 ) of integrated magnetic assembly  500  varies as the current applied to first winding  104  increases for various operating temperatures. As shown in  FIG. 8 , the inductance of the first winding assembly is relatively constant with changing current when compared to the first winding assembly of integrated magnetic assembly  100 . 
     In the exemplary embodiment, integrated magnetic assembly  100  is implemented in a multi-phase power converter, such as a multi-phase synchronous buck controller. Alternatively, integrated magnetic assembly  100  may be implemented in a multi-output power converter, such as a dual-output synchronous buck controller, or any other electrical architecture that enables integrated magnetic assembly  100  to function as described herein. 
       FIG. 9  is an exploded view of an alternative integrated magnetic assembly  900 . Unless specified, integrated magnetic assembly  900  is substantially similar to integrated magnetic assembly  100  (shown in  FIG. 1 ). Magnetic plate  112  and buffering layer  108  are omitted for clarity. In integrated magnetic assembly  900 , a magnetic base  902  includes a third U-core  904 , a second spacing member  906 , and a third winding  908 . Third U-core  904  includes a third surface  910  having a third winding channel  912  defined therein. Third surface  910  is substantially coplanar with first and second surfaces  122  and  142  of first and second U-cores  114  and  116 . 
     In the embodiment shown in  FIG. 9 , third winding channel  912  has substantially the same configuration as first and second winding channels  124  and  144  (i.e., a single bend of about 90 degrees). In alternative embodiments, third winding channel  912  may have a different configuration from one or both of first and second winding channels  124  and  144 , for example, by having a bend with a different angle, by having a different number of bends, or both. 
     In the embodiment shown in  FIG. 9 , second spacing member  906  connects third U-core  904  to first U-core  114  such that a gap  914  of relatively low magnetic permeability is formed between first and third U-cores  114  and  904 . In alternative embodiments, second spacing member  906  may connect third U-core  904  to second U-core  116  such that a gap of relatively low magnetic permeability is formed between second and third U-cores  116  and  904 . In the embodiment shown in  FIG. 9 , second spacing member  906  has substantially the same configuration has spacing member  118 . In alternative embodiments, second spacing member  906  may have a configuration substantially the same as spacing member  518  shown in  FIG. 5 , or any other configuration that enables integrated magnetic assembly  900  to function as described herein. 
     Third winding  908  is inductively coupled to third U-core  904 . Third winding  908  includes a fifth terminal side  916 , a sixth terminal side  918 , and an inductive section  920  interposed between fifth and sixth terminal sides  916  and  918 . Inductive section  920  is recessed within third surface  910 . In the embodiment shown in  FIG. 9 , integrated magnetic assembly  900  is particularly suited for use in high density power electronic circuits powered by a three-phase driver circuit configured to a supply a first current to first winding  104 , a second current to second winding  106 , and a third current to third winding  908 , wherein the first, second, and third currents are each out of phase with one another by about 120 degrees. 
       FIG. 10  is a flowchart of an exemplary method  1000  of assembling an integrated magnetic assembly, such as integrated magnetic assembly  100  shown in  FIG. 1 . A magnetic base, such as magnetic base  110  is provided  1002 . The magnetic base includes a first U-core including a first surface, a second U-core including a second surface, and a spacing member. A magnetic plate, such as magnetic plate  112  is provided  1004 . The magnetic base and magnetic plate are included in a magnetic core. The spacing member is connected  1006  to the first U-core and the second U-core such that the first and second surfaces are substantially coplanar and a gap having a relatively low magnetic permeability is formed between the first and second U-cores. The magnetic plate is coupled  1008  to the magnetic base such that the magnetic plate substantially covers the first and second surfaces. 
     Exemplary embodiments of integrated magnetic assemblies are described herein. A 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. 
     As compared to at least some integrated magnetic assemblies, in the systems and methods described herein, a magnetic core utilizes one or more spacing members configured to form a gap of relatively low magnetic permeability between multiple inductive cores within the magnetic core. Using a spacing member configured to form a gap of relatively low magnetic permeability between multiple inductive cores reduces the number of components needed to perform the same operations as compared to other integrated magnetic assemblies, and reduces the size of the integrated magnetic assembly, thereby increasing the maximum power density of the integrated magnetic assembly. Additionally, using a spacing member configured to form a gap of relatively low magnetic permeability between multiple inductive cores enables a more compact arrangement of inductive components that may be operated independently of one another. As a result, the position at which the windings enter and exit the integrated magnetic assembly can be easily modified to match the connection points of a given PWB, PCB, or other electronics board without affecting the independence of the inductive components. 
     Additionally, as compared to at least some integrated magnetic assemblies, in the systems and methods described herein, a magnetic core utilizes a unitary core for multiple inducting U-cores. Using a unitary core for multiple inductive cores provides better matching between the inductance of each core, thereby minimizing power losses and increasing the efficiency of the integrated magnetic assembly. 
     Additionally, as compared to at least some integrated magnetic assemblies, in the systems and methods described herein, a magnetic core utilizes a spacing member as a flux bridge between multiple inductive cores. Using a spacing member as a flux bridge between multiple inductive cores increases the inductance of at least one of the inductive cores under low current conditions, thereby reducing the likelihood of the integrated magnetic assembly entering a discontinuous phase (i.e., zero current phase). 
     The order of execution or performance of the operations in the embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention. 
     Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.