Patent Publication Number: US-11398333-B2

Title: Inductors with multipart magnetic cores

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to electrical components, and more particularly but not exclusively to inductors. 
     2. Description of the Background Art 
     Inductors are widely employed in various electrical circuits, such as filters and power converters. As a particular example, in a power converter, a single output inductor may be used to couple a switch node to an output node of the power converter. A coupled inductor may also be used to couple together the output phases of a multiphase power converter. The design of an electrical circuit is typically constrained by characteristics of components available to the designer. In terms of inductors, the designer selects an inductor available from a catalog of an electrical component vendor and makes design tradeoffs based on the characteristics of the inductor. The design tradeoffs involve compromises that hinder the performance of the electrical circuit. 
     SUMMARY 
     In one embodiment, an inductor comprises a multipart magnetic core and one or more wires. The multipart magnetic core may comprise a plurality of magnetic core parts. First and second magnetic core parts of the plurality of magnetic core parts may be disposed adjacent and magnetically coupled together to form one or more channels through which the one or more of wires may wind. The inductor provides an inductance of at least 40 nH for currents greater than 1 A and less than 60 A, and at least 20 nH for currents of at least 60 A. The magnetic core parts may have a rectangular, toroidal, cylindrical, planar, or some other shape. The magnetic core parts may be symmetrical or asymmetrical. The inductor may be a single inductor with only one wire, or a coupled inductor with two or more wires. 
     In another embodiment, a method of creating an inductor includes setting a first portion of an inductance profile of an inductor according to a target efficiency, setting a second portion of the inductance profile according to a target transient response, setting an inductance limit of the inductance profile according to a current protection limit, and generating the inductance profile to have the first portion, the second portion, and the inductance limit such that the inductor provides an inductance of at least 40 nH for currents greater than 1 A and less than 60 A, and at least 20 nH for currents of at least 60 A. 
     These and other features of the present invention will be readily apparent to persons of ordinary skill in the art upon reading the entirety of this disclosure, which includes the accompanying drawings and claims. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a three-dimensional view of an inductor with asymmetrical magnetic core parts in accordance with an embodiment of the present invention. 
         FIGS. 2-4  are various views of the inductor of  FIG. 1 . 
         FIG. 5  is a front view of an inductor with metal-to-metal contact between adjacent magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 6  is a three-dimensional view of an inductor with at least three magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 7  is a three-dimensional view of another inductor with asymmetrical magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 8  is a three-dimensional view of an inductor with asymmetrical magnetic core parts and a single channel in accordance with an embodiment of the present invention. 
         FIGS. 9-11  are various views of an inductor with symmetrical magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 12  is a three-dimensional view of an inductor with cylindrical magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 13  is a three-dimensional view of another inductor with cylindrical magnetic core part in accordance with an embodiment of the present invention. 
         FIG. 14  is a three-dimensional view of an inductor with toroidal magnetic core parts in accordance with an embodiment of the present invention. 
         FIG. 15  shows a plot of an inductance profile of an inductor in accordance with an embodiment of the present invention. 
         FIG. 16  shows plots of inductance profiles of inductors that have one-piece magnetic cores made of ferrites. 
         FIG. 17  shows a plot of inductance profile of an inductor that has a one-piece magnetic core made of iron powder. 
         FIG. 18  shows the plot of  FIG. 15  together with the plots of  FIGS. 16 and 17 . 
         FIG. 19  is a flow diagram of a method of creating an inductor in accordance with an embodiment of the present invention. 
         FIG. 20  shows the plot of  FIG. 15  with annotations that illustrate the method of  FIG. 19 . 
         FIG. 21  is a schematic diagram of a multiphase power converter in accordance with an embodiment of the present invention. 
         FIG. 22  is a schematic diagram of a single phase power converter in accordance with an embodiment of the present invention. 
     
    
    
     The figures are not drawn to scale. 
     DETAILED DESCRIPTION 
     In the present disclosure, numerous specific details are provided, such as examples of electrical circuits and components, to provide a thorough understanding of embodiments of the invention. Persons of ordinary skill in the art will recognize, however, that the invention can be practiced without one or more of the specific details. In other instances, well-known details are not shown or described to avoid obscuring aspects of the invention. 
       FIG. 1  is a three-dimensional view of an inductor  122 A in accordance with an embodiment of the present invention. In the example of  FIG. 1 , the inductor  122 A comprises a wire  120 - 1 , a wire  120 - 2 , and a multipart magnetic core  160 . As its name indicates, the multipart magnetic core  160  comprises two or more magnetic core parts. In the inductor  122 A, the multipart magnetic core  160  comprises a magnetic core part  140 - 1  and a magnetic core part  140 - 2 . 
     The inductor  122 A may be a coupled inductor or two inductors that are integrated together in one package. The inductor  122 A is depicted in  FIG. 1  with two wires  120 - 1 ,  120 - 2 . Generally, a coupled inductor or two inductors that are integrated together in one package, such as the inductor  122 A, comprise two or more wires. Each wire may have a first end that is coupled to a node of an electrical circuit, and an opposing second end that is coupled to another node the electrical circuit. For example, a first end of the wire  120 - 1  (e.g., see  FIG. 21 , end  141 ) may be electrically connected to a switch node of a power converter and a second end of the wire  120 - 1  (e.g., see  FIG. 21 , end  142 ) may be electrically connected to an output node of the power converter. In that example, a first end of the wire  120 - 2  (e.g., see  FIG. 21 , end  143 ) may be electrically connected to another switch node of the power converter and a second end of the wire  120 - 2  (e.g., see  FIG. 21 , end  144 ) may be electrically connected to the output node of the power converter. 
     The multipart magnetic core  160  is depicted in  FIG. 1  with two magnetic core parts  140 - 1 ,  140 - 2 . Generally, a multipart magnetic core in the present disclosure, such as the multipart magnetic core  160 , comprises two or more physically separate magnetic core parts. The magnetic core parts are disposed adjacent and magnetically coupled to one another. Magnetic core parts may have metal-to-metal contact, i.e., the surfaces of adjacent magnetic core parts may directly touch. Paper, air, magnetic material, non-magnetic material, or other medium may also be inserted between adjacent magnetic core parts depending on the design specification of the inductor. A magnetic core part may comprise a ferromagnetic metal (e.g., iron), ferrimagnetic compounds (e.g., ferrites), iron powder (e.g., carbonyl powders), or another magnetic material. The magnetic core parts may comprise the same magnetic material or different magnetic materials. 
     In the example of  FIG. 1 , the magnetic core parts  140 - 1  and  140 - 2  are adjacent and magnetically coupled together to form a channel  201 - 1  for accepting the wire  120 - 1  and a channel  201 - 2  for accepting the wire  120 - 2 . Each of the channels  201 - 1  and  201 - 2  provides a separate passageway through which a corresponding wire winds. In the inductor  122 A, the magnetic core parts  140 - 1  and  140 - 2  each provides corresponding upper and lower portions of a passageway. 
       FIG. 2  is a front view of the inductor  122 A in accordance with an embodiment of the present invention. In the inductor  122 A, the magnetic core part  140 - 1  has an E-shape and the magnetic core part  140 - 2  has a planar shape. The E-shape of the magnetic core part  140 - 1  has two trenches that when covered by a planar surface of the magnetic core part  140 - 2  form the channels  201 - 1  and  201 - 2 . 
       FIG. 3  is a top view of the inductor  122 A as seen looking at the magnetic core part  140 - 1 , in accordance with an embodiment of the present invention. As depicted by dashed lines, the channels  201 - 1  and  201 - 2  longitudinally extend front to back of the multipart magnetic core  160 . The wires  120 - 1  and  120 - 2 , which are depicted as dotted lines, go through the channels  201 - 1  and  201 - 2 , respectively. 
       FIG. 4  is a side view of the inductor  122 A as seen looking at the wire  120 - 2 , in accordance with an embodiment of the present invention. In the example of  FIG. 4 , the wire  120 - 1  (on the other side) and the wire  120 - 2  extend downward upon exit from the multipart magnetic core  160 . In that configuration, the wires  120 - 2  and  120 - 1  may extend down onto a via, pad, or other node of a printed circuit board (not shown) or other substrate. As can be appreciated, the wires  120 - 1  and  120 - 2  may also extend longitudinally outside of the multipart magnetic core  160  or have some other configuration. 
     In one embodiment, the wires  120 - 1  and  120 - 2  are single-turn wires. That is, in that embodiment, each of the wires  120 - 1  and  120 - 2  winds through the multipart magnetic core  160  only once. Generally, a wire may be wound through a multipart magnetic core one or more times depending on the design specification of the inductor. A wire may be wound on any of the magnetic core parts. For example, in the inductor  122 A, each of the wires  120 - 1  and  120 - 2  may be wound on at least one of the magnetic core parts  140 - 1  and  140 - 2 . 
     In the inductor  122 A, the magnetic core  140 - 1  is disposed adjacent and magnetically coupled to the magnetic core  140 - 2 . The inductor  122 A and other inductors in the present disclosure are depicted with a space between adjacent magnetic core parts for clarity of illustration. However, the magnetic core parts may also be directly in contact, as illustrated in the front view of an inductor  122 B shown in  FIG. 5 . In the inductor  122 B, a bottom surface of the magnetic core part  140 - 1  is depicted as making a metal-to-metal contact with a top surface of the magnetic core part  140 - 2 . The inductor  122 B is otherwise the same the inductor  122 A. 
     A multipart magnetic core may have more than two magnetic core parts. For example, the magnetic core part  140 - 1  may comprise multiple, smaller magnetic core parts that together form the magnetic core part  140 - 1 . As another example, additional magnetic core parts may be added to the multipart magnetic core  160  as now described with reference to  FIG. 6 . 
       FIG. 6  is a three-dimensional view of an inductor  122 C in accordance with an embodiment of the present invention. The inductor  122 C is a coupled inductor comprising a wire  120 - 1 , a wire  120 - 2 , and a multipart magnetic core  160 . In the inductor  122 C, the multipart magnetic core  160  comprises magnetic core parts  140 - 1 ,  140 - 2 , and  140 - 3 . In the inductor  122 C, the magnetic core part  140 - 2  has a planar shape and each of the magnetic core parts  140 - 1  and  140 - 3  has an E-shape. The E-shapes are arranged to face each other, with the planar shape interposed between them. The E-shape of the magnetic core part  140 - 1  has two trenches that when covered by a first planar surface of the magnetic core part  140 - 2  form the channels  201 - 1  and  201 - 2 . Similarly, the E-shape of the magnetic core part  140 - 3  has two trenches that when covered by a second, opposing planar surface of the magnetic core part  140 - 2  form the channels  201 - 3  and  201 - 4 . In contrast to the inductor  122 A, each wire of the inductor  122 C winds through two, separate channels. More particularly, in the inductor  122 C, the wire  120 - 1  winds through the channels  201 - 1  and  201 - 2 , whereas the wire  120 - 2  winds through the channels  201 - 3  and  201 - 4 . 
     An inductor may be a single inductor or a coupled inductor. A coupled inductor has two or more wires that go through a multipart magnetic core, whereas a single inductor has a single wire that goes through a multipart magnetic core. A coupled inductor may be converted to a single inductor by removing one or more extraneous wires. For example, as shown in  FIG. 7 , an inductor  122 D is the same as the inductor  122 A (e.g., see  FIG. 1 ) except that the inductor  122 D has a single wire. In the inductor  122 D, the wire  120 - 1  winds through the channels  201 - 1  and  201 - 2  formed by the magnetic core parts  140 - 1  and  140 - 2 . The inductor  122 D is otherwise the same as the inductor  122 A. 
       FIG. 8  is a three-dimensional view of an inductor  122 E in accordance with an embodiment of the present invention. The inductor  122 E is a single inductor that has been adapted from the coupled inductor  122 A. The inductor  122 E comprises a wire  120 - 1  and a multipart magnetic core  160 . In the inductor  122 E, the magnetic core part  140 - 1  has a U-shape and the magnetic core part  140 - 2  has a planar shape. The U-shape of the magnetic core part  140 - 1  has a single trench that when covered by a planar surface of the magnetic core part  140 - 2  forms the channel  201 - 1 . The inductor  122 B is otherwise the same as the inductor  122 A. 
     The inductors  122 D,  122 E, and other single inductors in the present disclosure may be employed in various electrical circuits. For example, as employed in a single-phase power converter, a first end of the wire  120 - 1  (e.g., see  FIG. 22 , end  141 ) may be electrically connected to a switch node of the power converter and a second end of the wire  120 - 1  (e.g., see  FIG. 22 , end  142 ) may be electrically connected to an output node of the power converter. 
     The magnetic core parts may have a symmetrical, asymmetrical, or other shape configuration. For example, whereas the magnetic core parts  140 - 1  and  140 - 2  are asymmetrical in the inductor  122 A,  FIG. 9-11  show an inductor  122 F with magnetic core parts  140 - 1  and  140 - 2  that are symmetrical. 
       FIG. 9  is a front view of the inductor  122 F in accordance with an embodiment of the present invention. The inductor  122 F is a coupled inductor comprising a wire  120 - 1 , a wire  120 - 2 , and a multipart magnetic core  160 . In the inductor  122 F, the multipart magnetic core  160  comprises magnetic core parts  140 - 1  and  140 - 2  that are symmetrical in shape. In the inductor  122 F, the magnetic core parts  140 - 1  and  140 - 2  each has an E-shape with two trenches. A trench of the magnetic core part  140 - 1  form a channel  201 - 1  with a trench of the magnetic core part  140 - 2 , and another trench of the magnetic core part  140 - 1  form a channel  201 - 2  with another trench of the magnetic core part  140 - 2 . In the inductor  122 F, the wire  120 - 1  winds through the channel  201 - 1 , whereas the wire  120 - 2  winds through the channel  201 - 2 . The inductor  122 F is otherwise the same as the inductor  122 A. 
       FIGS. 10 and 11  are a top view and a side view, respectively, of the inductor  122 F. The labeled features in  FIGS. 10 and 11  are the same as those shown in  FIGS. 3 and 4 , except for the shape of the magnetic core  140 - 1  and the magnetic core  140 - 2  as noted above. 
     A multipart magnetic core may have rectangular and/or non-rectangular (e.g., cylindrical or toroidal) magnetic core parts, as now described with  FIG. 12 . 
       FIG. 12  is a three-dimensional view of an inductor  122 G in accordance with an embodiment of the present invention. The inductor  122 G is a coupled inductor comprising a wire  120 - 1  and a wire  120 - 2 . In the inductor  122 G, the multipart magnetic core comprises magnetic core parts  140 - 1 ,  140 - 2 ,  140 - 3 , and  140 - 4 . In the inductor  122 G, each of the magnetic core parts  140 - 1  and  140 - 2  has a planar shape, and each of the magnetic core parts  140 - 3  and  140 - 4  has a cylindrical shape. The magnetic core parts  140 - 3  and  140 - 4  serve as posts that are capped by the magnetic core parts  140 - 1  and  140 - 2  at each end. In the inductor  122 G, the wire  120 - 1  is wound around the magnetic core part  140 - 3  and the wire  120 - 2  is wound around the genetic core part  140 - 4 . Generally, a wire may be wound one or more times around a corresponding magnetic core part. 
     In the inductor  122 G, the magnetic core parts  140 - 1 ,  140 - 2 ,  140 - 3 , and  140 - 4  are depicted as physically separate parts that are physically and magnetically coupled together to form a multipart magnetic core. Generally, two or more of the magnetic core parts may be fabricated as a single magnetic core part. For example, the magnetic core parts  140 - 1  and  140 - 3  may be fabricated as a single magnetic core part and, similarly, the magnetic core parts  140 - 2  and  140 - 4  may be fabricated as another single magnetic core part. The single magnetic core parts may be joined together to form the multipart magnetic core of the inductor  122 G. 
       FIG. 13  is a three-dimensional view of an inductor  122 H in accordance with an embodiment of the present invention. The inductor  122 H is a single inductor comprising a wire  120 - 1  and a multipart magnetic core. In the inductor  122 H, the multipart magnetic core comprises magnetic core parts  140 - 1 ,  140 - 2 ,  140 - 3 ,  140 - 4 , and  140 - 5 . In the inductor  122 H, each of the magnetic core parts  140 - 1 ,  140 - 2 ,  140 - 4 , and  140 - 5  has a planar shape and the magnetic core part  140 - 3  has a cylindrical shape. The magnetic core part  140 - 3  serves as a post that is capped at both ends by the magnetic core parts  140 - 1  and  140 - 2 . In the inductor  122 H, the wire  120 - 1  may be wound one or more times around the magnetic core part  140 - 3 . In the inductor  122 H, the magnetic core parts  140 - 4  and  140 - 5  serve as blocks that are interposed between the magnetic core parts  140 - 1  and  14 - 2  to provide structural support. The magnetic core parts  140 - 1 ,  140 - 2 ,  140 - 3 , and  140 - 4  are disposed to form a box with an open front and an open back, through which the wire  120 - 1  may be wound around the magnetic core part  140 - 3 . 
       FIG. 14  is a three-dimensional view of an inductor  122 J in accordance with an embodiment of the present invention. The inductor  122 J is a coupled inductor comprising a wire  120 - 1 , a wire  120 - 2 , and a multipart magnetic core  160 . In the inductor  122 J, the multipart magnetic core  160  has a toroidal shape that is formed by the magnetic core parts  140 - 1  and  140 - 2 . More particularly, the magnetic core parts  140 - 1  and  140 - 2  each has a half-toroidal shape; joining the magnetic core parts  140 - 1  and  140 - 2  together form the toroidal shape of the multipart magnetic core  160 . In the inductor  122 J, the wire  120 - 1  is wound one or more times around the magnetic core part  140 - 1  and the wire  120 - 2  is wound one or more times around the magnetic core part  140 - 2 . A single inductor version of the inductor  122 J may be fabricated by simply omitting either the wire  120 - 1  or wire  120 - 2 . 
     An inductance profile indicates an inductance of an inductor for a given current flowing through a wire of the inductor. In light of the present disclosure, it can be appreciated that the material and geometry (e.g., shape, size, and structural arrangement) of the magnetic core parts may be selected or designed to meet the inductance and current requirements of a target inductance profile. Other parameters of the inductor, such as wire material, wire gauge, wire winding configuration, medium between magnetic core parts, etc., may also be selected or designed to satisfy the target inductance profile. An electrical component vendor is thus able to commercially manufacture an inductor that meets a target inductance profile by combining the effects of different inductor parameters. 
       FIG. 15  shows a plot  301  of an inductance profile of an inductor  122  (i.e.,  122 A,  122 B,  122 C, . . . ) in accordance with an embodiment of the present invention. In the example of  FIG. 15 , the vertical axis indicates an inductance L in nanoHenry (nH) and the horizontal axis indicates current I in amp (A). As can be seen from the plot  301 , the inductor  122 , for each wire  120  (i.e.,  120 - 1 ,  120 - 2 , . . . ), has an inductance of at least 40 nH for currents that are greater than 1 A and less than 60 A, and an inductance of at least 20 nH for currents of at least 60 A. The inductance profile of the inductor  122  advantageously allows for a good balance between efficiency and transient response. 
       FIG. 16  shows plots of inductance profiles of inductors that have magnetic cores made of ferrites. In the example of  FIG. 16 , the vertical axis indicates an inductance L in nanoHenry (nH) and the horizontal axis indicates current I in amp (A). In the example of  FIG. 16 , a plot  302  of inductance profile is of an example inductor with a one-piece (as opposed to multipart) magnetic core made of ferrite, and a plot  303  of an inductance profile is of another example inductor with a one-piece magnetic core that is also made of ferrite. Inductors with ferrite magnetic cores typically have a steep saturation slope. When configured to provide high inductance, a ferrite magnetic core results in low saturation current as indicated by the plot  302 . When configured to provide low inductance, a ferrite magnetic core results in high saturation current as indicated by the plot  303 . 
     In the example of  FIG. 16 , the difference between the inductance profiles may be attributed to different geometries and/or percent composition of the ferrite magnetic cores. Different magnetic core parts that are made of ferrite (or other magnetic material) may be configured to have different geometries and/or percent composition to achieve a combined effect that meets the inductance-current requirements of a target inductance profile. That is, a multipart magnetic core may comprise magnetic core parts that are made of the same material but have different geometries and/or percent composition to meet the inductance-current requirement of a target inductance profile. For example, a first magnetic core part may be configured to have the plot  302  of inductance profile and a second magnetic core part may be configured to have the plot  303  of inductance profile, such that the resulting multipart magnetic core allows the inductor to have high inductance at low currents and low inductance at high currents. High inductance at low currents allows for better efficiency, while low inductance at high currents allows for better transient response. 
       FIG. 17  shows a plot  304  of inductance profile of an inductor that has a one-piece magnetic core made of iron powder. In the example of  FIG. 17 , the vertical axis indicates an inductance L in nanoHenry (nH) and the horizontal axis indicates current I in amp (A). Inductors that have iron powder magnetic cores typically have low inductance and high saturation current with shallow saturation slope as indicated by the plot  304 . As magnetic core materials, ferrite has steeper saturation slope and higher permeability than iron powder. 
     The inductance-current requirements of a target inductance profile may also be met by having magnetic core parts that have different materials, as now described with  FIG. 18 . 
       FIG. 18  shows the plot  301  of  FIG. 15  together with the plot  302  of  FIG. 16  and the plot  304  of  FIG. 17 . In the example of  FIG. 18 , the vertical axis indicates an inductance L in nanoHenry (nH) and the horizontal axis indicates current I in amp (A). As previously noted, the plot  302  of inductance profile is that of an inductor with a one-piece magnetic core made of ferrite and the plot  304  of inductance profile is that of an inductor with a one-piece magnetic core made of iron powder. An inductor  122  may be configured to have the plot  301  of inductance profile by having a multipart magnetic core comprising one or more magnetic core parts made of ferrite and one or more magnetic core parts made of iron powder. For example, in the inductor  122 A of  FIG. 1 , the magnetic core part  140 - 1  may be made of iron powder, while the magnetic core part  140 - 2  may be made of ferrite. The combined effect of the different magnetic materials may be visualized by combining the plot  302  with the plot  304 . The combined effect allows the inductor  122  to have high inductance at low current levels (as in the plot  302 ) and low inductance at high current levels (as in the plot  304 ). The geometries of the magnetic core parts may be configured as needed to make adjustments to the combined effect. 
       FIG. 19  is a flow diagram of a method of creating an inductor  122  in accordance with an embodiment of the present invention. In the example of  FIG. 19 , the method receives as inputs a size limit (block  401 ), a target efficiency (block  402 ), a target transient response (block  403 ), and a current protection limit (block  404 ). 
     The size limit dictates the maximum available volume and/or shape of the multipart magnetic core of the inductor  122 . The size limit may have to meet size restrictions of an application, such as available printed circuit board (PCB) area, proximity to surrounding structures, etc. 
     The target efficiency is the desired energy efficiency of the inductor  122 . The target efficiency may be specified as inductance below a predetermined current level. For example, the target efficiency may be the inductance of the inductor at or below a thermal design current (TDC). The target efficiency dictates the inductance of the inductor at low currents. The higher the inductance at low currents, the more efficient the inductor  122  and corresponding circuit. 
     The target transient response is the desired transient response of the inductor  122 . The target transient response dictates the inductance at medium to high current levels. The lower the inductance at medium to high currents, the faster the transient response of the inductor  122 . 
     The current protection limit is the maximum current that is allowed to flow through the inductor  122  or corresponding circuit (e.g., power converter). The current protection limit dictates the minimum inductance at a peak current level. 
     A target inductance profile of the inductor  122  may be created given the size limit, target efficiency, target transient response, and current protection limit as inputs (block  405 ). As a particular example,  FIG. 20  shows the plot  301  of the inductance profile of an inductor  122  with annotations that explain the aforementioned inputs. 
     In the example of  FIG. 20  the vertical axis indicates an inductance L in nanoHenry (nH) and the horizontal axis indicates current I in amp (A). In the example of  FIG. 20 , the size limit is a rectangular volume of 8×9×3 mm, the target efficiency is specified as an inductance range below TDC (see  FIG. 20, 351 ), the target transient response is specified as an inductance range between medium to high currents (see  FIG. 20, 352 ), and the current protection limit is specified as a minimum inductance at peak current. 
     Continuing the method of  FIG. 19 , the effect of combinations of different inductor parameters on the inductance profile of the inductor is determined (block  406 ) by static analysis (e.g., manual calculation), using a suitable simulation software, or other suitable evaluation technique. For example, the inductor  122 A of  FIG. 1  may be configured to have a magnetic core part  140 - 1  made of iron powder and a magnetic core part  140 - 2  made of ferrite. A simulation may be performed to check if that configuration allows the inductor  122 A to meet the inductance-current requirement of the target inductance profile. Other combinations of inductor parameters that may be checked for conformance with the target inductance profile include using the same material for magnetic core parts of different geometries, using the same material but with different percent compositions for magnetic core parts, etc. 
     The target inductance profile may be adjusted when the inductor cannot meet the inductance-current requirement of the target inductance profile given available combinations of inductor parameters (block  407  to block  405 ). 
     Once the combination of inductor parameters that meet the inductance-current requirement of the target inductance profile has been determined, a prototype of the inductor may be fabricated and tested (block  407  to block  408 ). The combination of inductor parameters is reevaluated when the prototype of the inductor does not meet the inductance-current requirement of the target inductance profile (block  409  to block  406 ). Otherwise, when the prototype of the inductor meets the inductance-current requirement of the target inductance profile, production versions of the inductor may be manufactured (block  409  to block  410 ). 
     As can be appreciated, an inductor  122  may be employed in various electrical circuits including power converters, such as DC-DC converters, AC-DC converters, inverters, etc. 
       FIG. 21  is a schematic diagram of a multiphase power converter  100 A in accordance with an embodiment of the present invention. The power converter  100 A receives an input voltage VIN at an input node  130  and generates an output voltage VOUT at an output node  131 . In the example of  FIG. 21 , the input voltage VIN is coupled to a capacitor CIN, and the output voltage VOUT is developed across an output capacitor COUT. The power converter  100 A may include a plurality of power stage circuits  110  (i.e.,  110 - 1 ,  110 - 2 , . . . ), one for each output phase. Two power stage circuits  110  are shown in the example of  FIG. 21  for illustration purposes. The power converter  100 A may have two or more power stage circuits  110 . 
     In the example of  FIG. 21 , a power stage circuit  110  includes a control circuit  112 , which controls switching of a high-side switch Q 1  and a low-side switch Q 2  to generate an output phase at a switch node SW. The switches Q 1  and Q 2  may be a metal-oxide semiconductor field effect transistor (MOSFET) or some other type of transistor. The control circuit  112  may drive the switches Q 1  and Q 2  by pulse-code modulation (PCM) or some other control scheme. As can be appreciated, the particulars of the control circuit  112  will vary depending on the topology and type of the power converter  100 A. 
     In the example of  FIG. 21 , an inductor  122  is a coupled inductor that couples the output phases of the power stage circuits  110  to the output node  131 . In the example of  FIG. 21 , the inductor  122  may be the inductor  122 A (see  FIG. 1 ), the inductor  122 B (see  FIG. 5 ), the inductor  122 C (see  FIG. 6 ), the inductor  122 F (see  FIG. 9 ), the inductor  122 G (see  FIG. 12 ), or the inductor  122 J (see  FIG. 14 ). 
     The inductor  122  comprises a multipart magnetic core  160  and a plurality of wires  120  (i.e.,  120 - 1 ,  120 - 2  . . . ) as previously described. In the example of  FIG. 21 , the wire  120 - 1  has an end  141  that is coupled to the switch node SW of the power stage circuit  110 - 1  and an opposing end  142  that is coupled to the output node  131 . Similarly, the wire  120 - 2  has an end  143  that is coupled to the switch node SW of the power stage circuit  110 - 2  and an opposing end  144  that is coupled to the output node  131 . 
       FIG. 22  is a schematic diagram of a single-phase power converter  100 B in accordance with an embodiment of the present invention. The power converter  100 B is the same as the power converter  100 A, except that the power converter  100 B has a single output phase. Accordingly, the power converter  100 B includes a single (instead of a coupled) inductor  122 . In the example of  FIG. 22 , the inductor  122  may be the inductor  122 D (see  FIG. 7 ), the inductor  122 E (see  FIG. 8 ), the inductor  122 H (see  FIG. 13 ), or the inductor  122 J without the wire  120 - 2  (see  FIG. 14 ). 
     Inductors with multipart magnetic cores and method of creating same have been disclosed. While specific embodiments of the present invention have been provided, it is to be understood that these embodiments are for illustration purposes and not limiting. Many additional embodiments will be apparent to persons of ordinary skill in the art reading this disclosure.