Coupled inductor and power supply module

Provided are a coupled inductor and a power module including the coupled inductor. A coupled inductor includes: a magnetic core, a first winding and a second winding, where a first passage is formed in the magnetic core; a part of the first winding and a part of the second winding pass through the first passage, and the first winding crosses with the second winding outside the first passage. Another coupled inductor includes: a magnetic core, a first winding and a second winding, where the magnetic core has a first passage and a second passage in parallel, both run through the magnetic core from one end face thereof to another opposite end face, where the first winding and the second winding both penetrate the first passage and the second passage, such that differently-named terminals of the windings are located on the same end face of the magnetic core.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Patent Application No. 201910013070.3, filed on Jan. 7, 2019, and Chinese Patent Application No. 201910796711.7, filed on Aug. 27, 2019. All of the aforementioned patent applications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to a coupled inductor and a power module, and belongs to the technical field of power electronics.

BACKGROUND

The inductor is a common electronic element in an integrated circuit that converts electrical energy into magnetic energy for storage. For instance, the inductor is an important component in a power supply module (i.e., a voltage regulating module (VRM), or a voltage converter) for realizing transformation between high voltage and low voltage. However, operational characteristics, such as current ripple, efficiency and dynamic operating speed, etc., of the power supply modules are subject to features such as inductor size, loss, inductance, etc. In this industry, magnetically coupled coils are typically used in manufacturing a coupled inductor to reduce the size of the inductor, so as to improve the performance of the power supply module.

Each winding in a coupled inductor may be measured, when the other windings are open or non-powered, to obtain a fixed inductance, known as self-inductance. The self-inductance may be decomposed into two components, all magnetic flux that corresponds to one of the two components passes through cross sections of the other windings, and thus this component is coupled with all the other windings, and may be referred to as magnetizing inductance (Lm). Another component is in no way coupled with the other windings, and may be referred to as leakage inductance (LK). Typically, the magnetizing inductance is much larger than the leakage inductance. By manipulating a ratio between, and magnitudes of, the magnetizing inductance and the leakage inductance, a waveform and a magnitude of a current ripple corresponding to a winding can be changed.

When the coupled inductor is used in a power supply module, there can be two types of coupling, i.e., a type of direct coupling and a type of inverse coupling, based on a connection mode of the switching unit and the inductors. An inversely coupled inductor refers to a coupled inductor connected as such that a current enters two windings from differently-named terminals of the windings, e.g., from a dotted terminal of one winding and a non-dotted terminal of the other winding, and the magnetic fluxes generated by the two windings cancel out each other. When a current enters through two terminals into two windings, respectively, to create magnetic fluxes that enhance each other, the two terminals are referred to as same-named terminals, e.g., the dotted terminals of the two windings, or the non-dotted terminals of the two windings. Put in another way, when the magnetic fluxes thus created weaken each other, the two terminals are referred to as differently-named terminals.

In an application of the VRM (voltage regulating module), the inversely coupled inductor can realize separation of dynamic inductance from static inductance, so that the same inductor can achieve smaller inductance in a dynamic state to improve the response speed, as well as increased inductance in a static state to achieve a smaller ripple current, thereby combining both dynamic responsiveness and small static ripples. In addition, the size can be reduced by the magnetic integration and the cancellation effect from the flux reversal. Hence in VRM applications, the technology of inversely coupled inductors is a hot spot in researches.

In a power supply module where an inversely coupled inductor is used, the input terminals of the coupled inductor should be differently-named terminals, i.e., a dotted terminal and a non-dotted terminal. However, in the layout of the existing inversely coupled inductor, it is inevitably required that the two input terminals (one of which is a dotted terminal while the other is a non-dotted terminal) of the inversely coupled inductor are disposed on different sides of the inductor in order to make the two electric currents, which are provided in parallel in the passage formed by the magnetic core, be in different directions to achieve the reversal and the cancellation effect of the magnetic flux in the magnetic core. This leads to different path lengths after the two-phase circuit is connected to the main board, and thus the impedances of the two phases will also be different, which is disadvantageous in current equalization.

SUMMARY

The present disclosure provides an inversely coupled inductor and a power supply module to address the above or other potential problems of the prior art.

It is an objective of the present disclosure to provide a coupled inductor including: a magnetic core, a first winding and a second winding, where a first passage is formed in the magnetic core; a part of the first winding and a part of the second winding pass through the first passage, and the first winding crosses with the second winding outside the first passage.

In a coupled inductor as described above, the magnetic core includes two side legs and two pillars which are oppositely arranged, respectively; and the two pillars are arranged between, and perpendicular to, the two side legs, and the first passage is defined by the side legs and the pillars.

In a coupled inductor as described above, the first winding includes a first section and a second section, which are oppositely arranged, and a third section, which is positioned between, and electrically connected to, the first section and the second section; the second winding includes a fourth section and a fifth section, which are oppositely arranged, and a sixth section, which is positioned between, and electrically connected to, the fourth section and the fifth section; the first section and the fourth section penetrate the first passage; and the third section crosses with the sixth section outside the first passage.

In a coupled inductor as described above, an electric current flows through the first section of the first winding in a direction opposite to an electric current flowing through the fourth section of the second winding.

In a coupled inductor as described above, a second passage is further formed in the magnetic core along a first direction, where the second passage is located on a right side of, and is parallel with, the first passage; the second section and the fifth section penetrate the second passage; and the third section crosses with the sixth section outside the first passage and the second passage.

In a coupled inductor as described above, an electric current flows through the second section of the first winding in a direction opposite to an electric current flowing through the fifth section of the second winding.

In a coupled inductor as described above, the magnetic core includes two side legs and at least three pillars, where the first passage is a space formed by the two side legs and two adjacent ones of the pillars; and the second passage is a space formed by the two side legs and another two adjacent ones of the pillars.

In a coupled inductor as described above, a decoupling leg is formed on at least one of the pillars and extends towards another adjacent one of the pillars, the decoupling leg being perpendicular to the pillar and forming, together with the adjacent pillar or a decoupling leg on the adjacent pillar, an air gap for adjusting an inversely coupling coefficient.

In a coupled inductor as described above, the first section, the second section, and the third section are integrally formed into one piece, and/or the fourth section, the fifth section and the sixth section are integrally formed into one piece.

In a coupled inductor as described above, the third section and the sixth section are plates, and the sixth section is located above the third section; the sixth section is formed with a first bump electrically connected to the fourth section and a second bump electrically connected to the fifth section, or, the fourth section includes a first bump and the fifth section includes a second bump; and the third section is formed with a first escape groove for the first bump to pass through and a second escape groove for the second bump to pass through.

In a coupled inductor as described above, the sixth section is a plate, the sixth section is provided with a through hole, the third section is provided in the through hole, a direction of an electric current flowing through the sixth section intersects with a direction of an electric current flowing through the third section.

In a coupled inductor as described above, the third section and the sixth section are mutually insulated and form a unibody structure.

In a coupled inductor as described above, the first section and the second section of the first winding and the fourth section and the fifth section of the second winding are injection-molded with the magnetic core into a unibody structure.

In a coupled inductor as described above, the inversely coupling coefficient is adjusted by controlling a width of a gap between the first section and the fourth section, or by controlling a width of a gap between the second section and the fifth section.

In a coupled inductor as described above, filler for adjusting the inversely coupling coefficient is filled between the first section and the fourth section, or between the second section and the fifth section.

In a coupled inductor as described above, the coupled inductor further includes a plurality of pads for input/output currents, and the plurality of pads are provided on one side of the first passage.

In a coupled inductor as described above, the magnetic core includes two side legs and a plurality of pillars, and the first winding crosses with the second winding on one of the pillars.

In a coupled inductor as described above, the first winding crosses with the second winding on one side of the first passage, or the first winding crosses with the second winding on both sides of the first passage.

In a coupled inductor as described above, the third section of the first winding and the sixth section of the second winding are provided separately on two sides of the first passage, and a vertical projection on the second winding by the third section of the first winding crosses with the sixth section of the second winding.

In a coupled inductor as described above, the first winding and/or the second winding are primarily made from a material having composite electric conductivity and/or strength.

Still another aspect of the present disclosure provides a coupled inductor, including: a magnetic core, a first winding and a second winding, where: a first passage and a second passage, which extend along a first direction, are formed in the magnetic core; the first passage includes a first end face and a second end face, which are oppositely arranged; the second passage is arranged in parallel with the first passage, and extends from the first end face to the second end face; a portion of the first winding and a portion of the second winding penetrate the first passage and the second passage, respectively, where the first winding runs through the first passage for N times while the second winding runs through the first passage for N+1 times, and the second winding runs through the second passage for N times while the first winding runs through the second passage for N+1 times, where N is an integer greater than or equal to one; two terminals of the first winding are provided on the first end face and the second end face, respectively, accordingly forming a first terminal and a second terminal of the coupled inductor; two terminals of the second winding are provided on the first end face and the second end face, respectively, accordingly forming a third terminal and a fourth terminal of the coupled inductor, where one of the first terminal and the third terminal of the coupled inductor is a dotted terminal and the other one is a non-dotted terminal, and the first terminal and the third terminal are both provided on the first end face.

In a coupled inductor as described above, the first terminal to the fourth terminal of the coupled inductor include a first pad to a fourth pad for electrical connection.

In a coupled inductor as described above, the first direction is a height direction.

In a coupled inductor as described above, the magnetic core is a flat type magnetic core.

In a coupled inductor as described above, the portion of the first winding located in the first passage and the portion of the second winding located in the first passage are provided alternatively with each other, and the portion of the first winding located in the second passage and the portion of the second winding located in the second passage are provided alternatively with each other.

In a coupled inductor as described above, the first winding further includes a connecting portion for connecting the portions of the first winding that penetrate the first passage and the second passage, and the second winding further includes a connecting portion for connecting the portions of the second winding that penetrate the first passage and the second passage.

In a coupled inductor as described above, the connecting portion of the first winding is located on the same side as the first end face or the second end face of the magnetic core and is exposed to air, the connecting portion of the second winding is located on the same side as the first end face or the second end face of the magnetic core and is exposed to air.

In a coupled inductor as described above, the connecting portions of the first winding and the second winding which are located on the same side as the first end face are arranged in parallel, the connecting portions of the first winding and the second winding which are located on the same side as the second end face are arranged in parallel.

In a coupled inductor as described above, the connecting portion of the first winding on the same side as the first end face crosses with the connecting portion of the second winding on the same side as the second end face, the connecting portion of the first winding on the same side as the second end face crosses with the connecting portion of the second winding on the same side as the first end face.

In a coupled inductor as described above, the first passage and the second passage are both filled with a magnetic material which dads the portions of the first winding and the second winding that are located in the first passage and the second passage.

In a coupled inductor as described above, the portions of the first winding and the second winding that are located in the first passage and the second passage are both formed as cylinders.

In a coupled inductor as described above, the magnetic core is a dust type magnetic core that has a relative permeability of less than 200 and has distributed air gaps.

In a coupled inductor as described above, the magnetic core includes two side legs which are oppositely arranged, and at least three pillars arranged between the two side legs, and the first passage and the second passage are defined by the adjacent three pillars and the two side legs.

In a coupled inductor as described above, air gaps are formed in both of the two side legs to communicate with the first passage and the second passage.

In a coupled inductor as described above, the first passage and the second passage are both filled with a magnetic material, and the air gaps run through the magnetic material.

In a coupled inductor as described above, an air gap is formed in two pillars which are separated by one pillar, respectively, to communicate with the first passage and the second passage.

In a coupled inductor as described above, air gaps are formed in the pillar separating the two pillars, the air gaps communicating at two ends with the first passage and the second passage, respectively.

In a coupled inductor as described above, one of the side legs and a portion of the three pillars are integrally formed into an “E” shaped magnetic core.

In a coupled inductor as described above, the magnetic core is a ferrite type magnetic core having a relative permeability of greater than 200.

In a coupled inductor as described above, an outer surface of the magnetic core is provided with a pin for electrical connection.

In a coupled inductor as described above, the first winding and the second winding are fabricated by a printed circuit board (PCB) printing process.

In a coupled inductor as described above, the coupled inductor is a multi-phase coupled inductor.

An aspect of the disclosure provides a power supply module, including a first switching unit, a second switching unit and the coupled inductor as described above, where a first winding of the coupled inductor includes a first terminal and a second terminal, a second winding of the coupled inductor includes a third terminal and a fourth terminal, and one of the first terminal and the third terminal of the coupled inductor is a dotted terminal and the other one is a non-dotted terminal, the first terminal is connected to the first switching unit, the third terminal is connected to the second switching unit, the second terminal and the fourth terminal serve as outputs for the power supply module.

The power supply module as described above further includes: a main board, a packaged chip module and a heatsink, where the coupled inductor, the packaged chip module and the heatsink are stacked in the same order over the main board.

According to the coupled inductor and the power supply module provided in the present disclosure, two windings can intersect outside the first passage of the magnetic core, allowing for a dotted terminal and a non-dotted terminal of the input/output pins of the coupled inductor to be located on the same side, which is convenient to use and advantageous in current equalization. Additionally, a dotted terminal and a non-dotted terminal of the two windings may also be provided on the same end face of the inversely coupled inductor, so that no extra pin or connecting wire is needed when a power chip or a switching unit is located between the inversely coupled inductor and the heatsink, which is advantageous in reducing direct current impedance and improving space utilization.

Advantages of additional aspects of the present disclosure will be set forth in part in the description which follows, and some of the advantages will become apparent from the following descriptions, or be acquired in practicing the present disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure will be described in detail below, and examples of the embodiments are illustrated in the drawings, where the same or similar reference numerals throughout the specification are used to represent the same or similar elements, or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the present disclosure, rather than to be construed as limiting.

In the description of the present disclosure, it is to be understood that the terms “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside” and/or the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings for the mere purpose of facilitating and simplifying the description of the present disclosure, rather than indicating or implying that the device or element has to have a particular orientation or be configured and/or operated in a particular orientation, and hence may not be construed as limiting the present disclosure.

In addition, the terms “first” and “second” are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features being indicated. Thus, features qualified by “first” and “second” may include at least one of the features, either explicitly or implicitly. In the description of the present disclosure, “a plurality” means at least two, such as two, three, etc., unless specifically defined otherwise.

Unless explicitly stated and defined otherwise, in the present disclosure, the terms “installed”, “coupled”, “connected”, “fixed” and the like shall be understood broadly, e.g., they may indicate a fixed connection, a detachable connection, a unibody, a direct connection, an indirect connection via an intermediate medium, a communication within two elements or the interaction between two elements, unless explicitly defined otherwise. For persons of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood on a case-by-case basis.

In the description of the present specification, the description with reference to the terms “an embodiment”, “some embodiments”, “example”, “specific example”, “some examples” or the like means a specific feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the specific feature, structure, material or characteristic described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples or features thereof described in the specification may be combined by persons skilled in the art if no conflict is thus created.

FIG.1is a schematic structural view of a coupled inductor. As shown inFIG.1, the coupled inductor provided in this example is a coupled inductor in which same type terminals are located on the same side of the inversely coupled inductor, and that includes a magnetic core1, a first winding21and a second winding22. In this embodiment, the same type terminals can all be input terminals or can all be output terminals. In other embodiment, one terminal of the same type terminals is a dotted terminal while the other terminal is a non-dotted terminal.

The magnetic core1includes two side legs10disposed opposite to each other, and pillars11and12that are disposed between, and perpendicular to, the two side legs10. Both ends of the side legs10are joined to both ends of the pillars11and12to form a complete magnetic loop, that is, the side legs10and the pillars11and12define a first passage31. In some examples, a “U” shaped magnetic leg may be used instead of the side legs10and the pillars11and12. When the “U” shaped magnetic leg is used, only two magnetic legs engaged together are needed to form the magnetic core1having the first passage31. The first passage31has two opposite end faces, namely a first end face39aof the passage and a second end face39bof the passage.

A portion of the first winding21and a portion of the second winding22are both penetrate the first passage31, and another portion of the first winding21and another portion of the second winding22cross with each other outside the first passage31. TakingFIG.1as an example, the first winding21and the second winding22are both wound on the pillar12on the left, and the first winding21and the second winding22, which are mutually insulated, cross with each other on the side of the first end face39aof the passage outside the first passage31.

FIG.2is a top view ofFIG.1, illustrating the arrangement of the terminals (or pins, pads) at the same time. The first winding21and the second winding22cross with each other on the side of the first end face39aof the passage, and on the opposite side, i.e., the side of the second end face39bof the passage, pads51to54are provided as input and output pins of the coupled inductor. Specifically, pads51and52are provided as input pins on the left side inFIG.2, and pads53and54are provided as output pins on the right side inFIG.2. The first winding21is electrically connected at one terminal to the pad52, and at the other terminal to the pad53. The second winding22is electrically connected at one terminal to the pad51, and at the other terminal to the pad54. As used herein, the terms “pad” and “pin” both refer to terminals via which a unit is electrically connected to the outside. In the following, for ease of use, “pad” and “pin” will be used interchangeably, and will be both labeled with the same reference numerals.

Still referring toFIGS.1and2, in this example, the first winding21includes a first section211, a second section212, and a third section213that is located between, and serves to join, the first section211and the second section212. The second winding22includes: a fourth section221, a fifth section222, and a sixth section223that is located between, and serves to join, the fourth section221and the fifth section222. The first section211of the first winding21and the fourth section221of the second winding penetrate the first passage31of the magnetic core1; the third section213of the first winding21and the sixth section223of the second winding22cross with each other on the side of the first side end face39aoutside the first passage31.

The arrows in the figures indicate the directions in which the electric currents flow through the first winding21and the second winding22. The electric current flows downwards through the portion of the first winding21located within the first passage31(i.e., the first section211), and the electric current flows upwards through the portion of the second winding22located within the first passage31(i.e., the fourth section221). That is, in the coupled inductor provided in this embodiment, the electric currents flow in opposite directions through the portions of the first winding21and the second winding22that penetrate the first passage. The expression that the electric currents flow in opposite directions means that the two windings have opposite magnetic fluxes in the magnetic leg they encircle.

By arranging the current flow directions as the above, the magnetic fluxes induced in the magnetic core1by the first winding21and the second winding22are in opposite directions, forming an inversely coupled inductor. At the same time, the input pin of the first winding21(i.e., the pad52) and the input pin of the second winding22(i.e., the pad51) may both be located on the left side inFIG.2, while the output pin of the first winding21(i.e., pad53) and the output pin of the second winding22(i.e., pad54) are both located on the right side inFIG.2. In other words, the inductor provided in the present embodiment is inversely coupled, and by having the first winding21and the second winding22cross with each other outside the first passage31, the same type terminals (i.e., the input terminals52and51) can be located on the same side of the inductor. It not only improves the symmetry of the two-phase circuit with the inversely coupled inductor, but also offers more convenience in applications.

It should be understood that this embodiment does not limit the electric current to flow in the above manner. Rather, this embodiment merely requires that portions of the two windings pass through a passage formed by the magnetic core, and that an intersection is created outside the passage for portions of the two windings other than those penetrating the passage of the magnetic core. Any other structural features may be selected or rearranged, either individually or in combination, as long as no contradiction is created.

FIG.3is a schematic structural view of another coupled inductor, andFIG.4is a top view ofFIG.3. As shown inFIGS.3and4, the coupled inductor of this example is different from that ofFIGS.1and2in that the magnetic core1includes three pillars, i.e., pillars11to13, where two side legs10and the pillars11and12form the first passage31, and the two side legs10and the pillars12and13form a second passage32. That is, the magnetic core1ofFIGS.3and4forms an “8” shaped magnetic loop. Of course, in some examples, it is also possible to arrange more pillars12between the two side legs10, so that more passages may be formed by the side legs10and the pillars12. In this example, as compared againstFIGS.1and2, the second section212of the first winding21and the fifth section222of the second winding22also penetrate the second passage32of the magnetic core1.

In this example, the electric currents flow in opposite directions not only for the first section211of the first winding21and the fourth section221of the second winding22, but also for the second section212of the first winding21and the fifth section222of the second winding22.

Through the above arrangement, the first winding21and the second winding22are both wound around the pillar12, and the magnetic flux generated on the pillar12is simultaneously shunted to the side legs11and13, which is advantageous for improving the symmetry and uniformity of the magnetic loop, and reducing magnetic loss. The first and second windings21and22are insulated from each other, and cross with each other outside the passages31and32, i.e., on the side of the first end face39aof the passage. Referring toFIG.4, pads51to54are formed on the other side of the passages31and32(i.e., on the side of the second end face39bof the passage).

InFIGS.3and4, the arrows in the figures indicate the directions in which the electric currents flow through the first winding21and the second winding22. Similar toFIGS.1and2, the electric currents flow in opposite directions through the portions of the first winding21and the second winding22that are in the first passage31(i.e., the electric currents flow in opposite directions through the first section211of the first winding21and the fourth section221of the second winding22). Similarly, the electric currents also flow in opposite directions through the portions of the first winding21and the second winding22that are in the second passage32(i.e., the electric currents flow in opposite directions through the second section212of the first winding21and the fifth section222of the second winding22). Thus, the magnetic fluxes induced in the pillar12by the two windings are in opposite directions, forming an inversely coupled inductor. Compared against the embodiment shown inFIGS.1and2, the inductor shown inFIGS.3and4is more conducive to achieving an inversely coupled inductor with more inductance or saturation current when the size is the same. Put in other words, it is more advantageous in reducing the size of the inductor. Since the first winding21and the second winding22are arranged to cross with each other outside the first passage31and the second passage32of the magnetic core1, the same type terminals (i.e., the input terminals52and51) can be located on the same side of the inductor. For example, pads51and52are input pins that are arranged on the left side of the inductor, while pads53and54are output pins that are arranged on the right side of the inductor.

The above arrangement is advantageous in improving the symmetry of the two-phase circuit, and is easy to use. At the same time, since the two windings21and22cross with each other outside of the passages31and32formed in the magnetic core1and the pins of the inductor are all disposed on the other sides of the passages, it becomes possible, when fabricating the inductor, to pre-fabricate the magnetic core1and windings21and22separately, and then insert the windings21and22into the passages31and32of the magnetic core1, and form the pads51to54as input and output pins on the other sides of the passages31and32, arriving at a more simplified and efficient fabricating process, and also being conducive to modular product design. Since the two windings21and22cross with each other outside of the passages31and32formed in the magnetic core1, the mutual insulation treatment at the crossed portions of the windings is also made easier. In addition, the input and output pins (i.e., pads51to54) of the windings21and22are in a plane that extends along a vertical direction. This is advantageous in conducting heat in the vertical direction, and the upper surface of the inductor (i.e., the plane where the windings21and22intersect as inFIGS.3and4) may serve as a mounting plane for a heatsink to facilitate conduction and dissipation of heat in the vertical direction.

Furthermore, although the windings21and22are shown as a unibody structure inFIGS.3and4, individual sections of the windings21and22may also be discrete structures. Additionally, in some examples, it is possible for one of the windings21and22to be a discrete structure while the other to be a unibody structure.

FIG.5is a schematic structural view of another coupled inductor, andFIG.6is a top view ofFIG.5. As shown inFIGS.5and6, the coupled inductor of this example is different from that ofFIGS.3and4in that the first winding21is inserted into the passages31and32of the magnetic core1from the side of the first end face39aof the passage, and the second winding22is inserted into the passages31and32of the magnetic core1from the side of the second end face39bof the passage.

Still referring toFIG.6, in this example, the pads51and54are located on the same side of the magnetic core1as the first winding21, that is, the pad51and the pad54are also located on the side of the first end face39aof the passage. The pads52and53are located on the same side of the magnetic core1as the second winding22, that is, the pads52and53are also located on the side of the second end face39bof the passage. Although the first winding21and the second winding22are located on different end faces, the first winding21and the second winding22still achieve a crossing outside the passages31and32. The pads51and52, which are provided as input terminals, are both on the left side inFIG.6, albeit on different end faces of the magnetic core1. Similarly, the pads53and54, which are provided as output terminals, are both on the right side inFIG.6, albeit on different end faces of the magnetic core1. Moreover, with the above arrangement, the first winding21and the second winding22can be insulated from each other without special treatment, so that the first winding21and the second winding22can be made using identical parts, thereby reducing the number of part types that need to be separately manufactured, which in turn reduces costs.

FIG.7is a schematic structural view of another coupled inductor, andFIG.8is an exploded view ofFIG.7. As shown inFIGS.7and8, the coupled inductor of this example differs from that ofFIGS.3and4in that it further includes a third winding23and a fourth winding24. The first winding21and the second winding22are inserted into the passages31and32of the magnetic core1from the side of the first end face39aof the passage, and the third winding23and the fourth winding24are inserted into the passages31and32of the magnetic core1from the side of the second end face39bof the passage. Portions of the first winding21and the second winding22cross with each other outside the passages31and32in a manner similar to the previous embodiments. Meanwhile, portions of the third winding23and the fourth winding24also cross with each other outside the passages31and32, except for that the first winding21and the second winding22cross with each other on the side of the first end face39aof the passage, while the third winding23and the fourth winding24cross with each other on the side of the second end face39bof the passage. By inserting more windings in the passages31and32of the magnetic core1, a multi-phase circuit can be integrated to increase the power density. It can be understood that this example is equally applicable to an inductor having one passage or more than two passages.

FIG.9is a schematic structural view of another coupled inductor, andFIG.10is an exploded view ofFIG.9. As shown inFIGS.9and10, the coupled inductor provided in this example is different from that ofFIGS.3and4in that at least one of the first winding21and the second winding22is a multi-turn winding wound around the pillar12to allow larger inductance or other properties for the inductor. It can be understood that this example does not limit the first winding21and the second winding22to have multi-turns, nor that the number of turns be equal for the first winding21and the second winding22.

FIG.11is a schematic structural view of another coupled inductor, andFIG.12is a schematic structural view after a part of the structure ofFIG.11is dissembled. As shown inFIGS.11and12, the coupled inductor of this example differs from that ofFIGS.3and4in that the windings inFIGS.3and4are unibody structures while those in this example employ the discrete structure as below.

In this example, the portions of the windings21band22bwhich cross with each other outside the passages31and32of the magnetic core1are separately fabricated from the windings21aand22awhich penetrate the passages31and32. When the inductor is being assembled, the windings21aand21bare electrically connected to complete the first winding21. Similarly, the windings22aand22bare electrically connected to complete the second winding22.

Specifically, as shown inFIGS.11and12, the windings21band22bare both provided as plate-like structures, and the windings21band22bare arranged in a stacking manner, which are mutually insulated. Two bumps are provided on the winding21b, while corresponding openings for allowing the two bumps to pass through are provided on the winding22b. When21band22bare stacked at a proper pitch, then22band22acan be made electrically connected, while the winding21bis electrically connected to the two windings21avia the two bumps, respectively. Of course, two lower bumps may also be provided at locations on the lower surface of the winding22bcorresponding to the windings22afor realizing electrical connection with the two windings22a. Of course, in some examples, the above-described bumps may also be provided on the windings21a.

FIG.13is a bottom view of a coupled inductor illustrating the pinout at the bottom. UsingFIG.13as an example, which is a bottom view of the coupled inductor shown inFIG.11andFIG.12, pins51and52are same type terminals, and pins53and54are also same type terminals. Pins51and54are electrically connected via windings22aand22b, and pins52and53are electrically connected via windings21aand21b. A winding22aelectrically connected to the pin51and a winding21aelectrically connected to the pin53are disposed in the first passage31, and a winding21aelectrically connected to the pin52and a winding22aelectrically connected to the pin54are disposed in the second passage32.

In addition,FIG.13also shows that the pillars11to13disposed between the two side legs10inFIGS.11and12can be replaced with a double-sided “E” shaped magnetic core. Specifically, the magnetic core1includes a double-sided “E” shaped magnetic core, and two “I” shaped magnetic cores which are used for connecting both ends of the double-sided “E” shaped magnetic core to form a magnetic loop. As shown inFIG.13, a passage31is assembled and formed on the “E” shaped side in the upper drawing, and a passage32is assembled and formed on the “E” shaped side in the lower drawing.

FIG.14is the structure of another coupled inductor. It is different fromFIG.12in that both side legs10are provided with magnetic bumps101on the side of the first end face39aof the passage, and the windings21band22bare provided with positioning grooves26. A matching between the magnetic bumps101and the positioning grooves26helps aligning the windings21band22bduring assembling. This may, for example, prevent the windings21band22bfrom displacement or short-circuited to each other. Windings21aand22aare provided in the passages31and32. The input and output pins of the inductor are drawn out on the side of the second end face39bof the passage.

FIG.15shows an alternative structure for the windings21band22b.FIG.15differs fromFIGS.11and12in that the windings21band22bare integrally packaged in a unibody structure.FIG.16is a sectional view taken along line A-A ofFIG.15. As shown inFIG.16, the windings21band22bare both packaged in the insulating encapsulant9, with the lower surface being provided with pads251to254. The pads252and254are used to be electrically connected to the winding21a, and the pads251and253are used to be electrically connected to the winding22a. The electrical connection between the pads251-254and their respective windings can be achieved using via plating or other metallizing methods. For example, the pad253and the winding22binFIG.16can be electrically connected using via plating, so can the pad254and the winding21busing via plating. Of course, the electrical connection can also be realized using other metallizing methods.

It should be understood that the winding module shown inFIG.16can also be fabricated using a conventional PCB or laminated bus bar process, or using various packaging processes such as a package process using a lead frame for packaging and extracting pads.

Various methods can be used to adjust the coupling coefficient for the coupled inductor of the above embodiment.FIG.17is a schematic structural view of a coupled inductor, andFIG.18is a top view ofFIG.17.FIGS.17and18differ fromFIGS.3and4in that a magnetic leg is drawn from the middle of the pillar12towards the pillars11or13, respectively, as a decoupling leg121. The decoupling leg121is perpendicular to the pillar12, and forms an air gap4with its opposing pillar11or13. The coupling coefficient can be adjusted by controlling the height t of the air gap4. Of course, in some examples, one or more decoupling legs121may also be formed on one or more of the pillars.

It should be understood that the manner of forming the air gap is not limited to the above. For example, a design in which the air gap4is also formed by the double-sided “E” shaped magnetic core is shown inFIG.13.

Further, in order to adjust the coupling coefficient of the inductor, in addition to the provision of the air gap4and further adjustment of the height of the air gap4, various methods may also be employed, such as adjusting the spacing between the windings or the width of the magnetic legs. That is, the coupling coefficient of the coupled inductor of this example can be adjusted by any one or more of the following methods: providing the air gap4, adjusting the height t of the air gap4, adjusting the spacing between the windings21and22(including but not limited to the spacing between any two of the sections of different windings, such as the first section211of the first winding21, the second section212of the first winding21, the fourth section221of the second winding22, and the fifth section222of the second winding22), adjusting the spacing between two adjacent pillars, or providing magnetic materials with different magnetic properties (e.g., magnetic permeability) between adjacent pillars. Adjusting the coupling coefficient in a variety of ways can improve the flexibility in tuning the coupled inductor, offering a wider range of applications. Moreover, the air gap4is within the structure of the inductor, which can reduce the magnetic field leakage, reducing the magnetic interference intensity.

It should be noted that, for a distributed air gap, or a coupled inductor having the structure shown inFIG.19, a coupling coefficient can be adjusted by altering the space between the portion of the winding21and the portion of the winding22that are located in the passage31or32of the magnetic core1. Referring toFIG.19, the coupled inductor differs from that ofFIG.12in that the passages31and32are filled with filler6, and the cross-sections of the passages31and32and the cross-section of the first winding21aor22ain the passages31and32are identically shaped. For the coupled inductor of the above structure shown inFIG.19, the coupling coefficient can be controlled not only by adjusting the space t between the windings, but also by controlling the material properties of the filler6between the windings. For example, filling the region6with a non-magnetic material can increase the coupling coefficient.

FIG.20is a schematic structural view of another coupled inductor.FIG.20differs fromFIG.12in that the windings inFIG.12cross with each other by cross-stacking the windings21and22outside the passages31and32. That is, the windings21and22cross with each other inFIG.12by different layers, whileFIG.20illustrates an implementation in which the windings21and22cross with each other in the same layer (i.e., cross in the same plane).

Specifically, the windings21band22bare both plate-like structures, and a through hole is formed in the winding22b, and the winding21bis embedded in the through hole, so that the windings21band22bare in the same plane. There is a gap between the winding22band the winding21bwhich are insulated from each other. The winding22bis electrically connected to the winding22ain the magnetic core1, and the winding21bis electrically connected to the winding21ain the magnetic core1. The electric currents flow through the windings21band22bin the directions as indicated by the arrows inFIG.19, which cross with each other, thus achieving the mutual crossing of the two windings in the same plane. The electric current in the winding21bflows along the arrow, while the electric current in the winding22bflows around the winding21b, yet generally in a direction that crosses with the direction of the current in the winding21b.

In addition,FIG.20also illustrates that the magnetic core1is formed by assembling three segments of magnetic legs having a centralized air gap. The coupling coefficient can be adjusted by controlling the height of the air gap4.

FIG.21is a schematic structural view of another coupled inductor.FIG.21differs fromFIG.20in that the windings21aand22aare integrally injection molded, having distributed air gaps, and the coupling coefficient can be tuned by controlling the spacing t between the windings or the magnetic properties (e.g., magnetic permeability) of the filler in the region6between the windings.

In the coupled inductor as shown inFIGS.20and21, the windings21band22bcross with each other in the same plane, eliminating the stacking of the windings, which is advantageous in reducing the height of the inductor, while simplifying the fabrication of the windings21band22band the structure of the inductor.

FIG.22is an alternative example from the windings21band22bofFIGS.20and21. As shown inFIG.22, the windings21band22bmay be integrally formed, packaged in the insulating material9, and then be mounted onto the magnetic core1below and the windings21aand22aas shown inFIGS.20and21to form a complete coupled inductor.

FIG.23is a sectional view taken along line A-A ofFIG.22. As shown inFIG.23, the windings21band22bare both packaged in the insulating encapsulant9, with the lower surface being provided with pads251to254. The pads252and254are used to be electrically connected to the winding21a, and the pads251and253are used to be electrically connected to the winding22a. The electrical connection between the pads251to254and their respective windings21to22can be achieved using via plating or other metallizing methods. For example, the pad251and the winding22binFIG.22can be electrically connected using via plating, and so can the pad252and the winding21busing via plating. Of course, the electrical connection can also be achieved using other metallizing methods.

It should be understood that the winding module shown inFIG.23can also be fabricated using a conventional PCB or laminated bus bar process, or using packaging processes such as a package process using a lead frame for packaging and extracting pads.

In this example, the crossed windings21band22bmay be integrally formed to improve the modular manufacturing process of the inductor, lower the cost, and improve the reliability of the overall structure, while simplifying the structure and facilitating the assembly process. It is also possible to form other conductive traces in the crossed-windings module. Pads can be formed over the crossed windings, and other elements, such as capacitors or resistors, can be arranged. This offers more flexible application options. The integration and space utilization of the inductor can be further improved.

FIGS.24athrough24dillustrate a method for fabricating a coupled inductor. A conductive structural member is given by a conductive member including a pillar20aand a connecting piece20bas shown inFIG.24aorFIG.24b. A plurality of pillars20aare provided on a surface perpendicular to20b, which may be made by, for example, etching on a copper sheet, or stamping, or welding or engraving or the like.

Further, it is also illustrated inFIG.24athat in order to enhance the strength and other characteristics of the conductive leg20a, a high-conductivity-material95, such as copper or silver, may be coated on a high-strength material91, such as steel. Thus, the rigidity and strength of the conductive leg20acan be greatly improved, and the deformation of the conductive leg20acan be reduced during the injection molding process. Although the conductivity of the core-reinforced structure91will be much worse than that of the high-conductivity-material95, however, considering that, in the case of high frequency applications, electric currents flow mostly on the surface of the conductive leg20adue to the skin effect, that is, most of the electric currents will be flowing in the highly conductive layer of91, only a small amount of current flows in the core structure91. Thus, this solution is suitable for the application of high frequency magnetic elements.

Additionally, a layer of other material71may be further coated on the outer surface of the conductive leg20aand the connecting piece20bbefore inject molding the upper magnetic material10as shown inFIG.24b. The coated material71may be, e.g., a high-voltage-resistant insulating material to raise the voltage rating between the conductive legs20a, or an etch-resistant material to avoid damaging the internal magnetic material characteristics when the connecting piece20bis being etched.

Then, as shown inFIG.24b, the magnetic material is injected into the conductive structural member shown inFIG.24ausing a mold. Since the leg20ais structurally reliable because it is formed integrally with the connecting piece20b, the impacts on the leg20aduring the injection molding of the magnetic material, e.g., dust type magnetic core material, can be controlled and absorbed. Particularly, when the leg20ais of low height and a cylinder, particularly a conical cylinder, the displacement and deformation between the legs20aare much smaller.

Then, as shown inFIG.24c, a groove29is carved into the connecting plate20bby etching or engraving, dividing the connecting plate into two partitions to form the cross between the windings outside the passage of the magnetic core.

Finally, as shown inFIG.24d, several pads50are formed at the other end of the passage.

It can be understood that cutting can also be performed according to the needs of the process, for example, cutting a molding member of a panel into individual magnetic units; or applying insulation treatment onto the surface after the cutting; or deflashing a conductive portion that is partially covered by magnetic material, i.e., removing a portion of the magnetic material to expose the conductive portion, such as the pads50.

In general, the coupled inductor in the above examples have the following advantages: the crossing portion of the coupled inductor is outside the passage of the magnetic core, which facilitates the mutual insulation treatment of the crossing portion; the two-phase output pins of the coupled inductor are on the same side of the coupled inductor, offering convenience to the customer during practical application, and the improved symmetry of the two-phase circuit is conducive to current equalization; the fabrication of the windings and the magnetic core can happen in parallel, which facilitates modular product design, simplifies the process and reduces the cost. Moreover, since the windings in the passage are connected along the vertical direction to the windings for crossing outside the passage, the heat dissipation of the inductor in the vertical direction is facilitated.

FIGS.25to28are structural views of coupled inductors which are formed on the basis of the foregoing coupled inductors and have more phases. For ease of illustration, all descriptions are given using an example of integration of three coupled inductors. Of course, more coupled inductors can still be integrated as needed in practical applications. As shown inFIGS.25to28, the magnetic core includes two side legs10, and more of pillars11to17, where the first winding and the second winding cross with each other on one of the pillars.

FIG.25is a schematic structural view of three coupled inductors integrated in a parallel connection, in which the pillars of two adjacent coupled inductors in tight contact are integrated together to realize magnetic loop multiplexing, thereby improving the utilization of individual magnetic loops in the multi-phase coupled inductor. This can increase the efficiency for an inductor of the same size, or reduce the size for an inductor of the same efficiency. Integration as such can shorten the total length from the left to the right of the multi-phase coupled inductor. For instance, inFIG.25, the width of two pillars can be reduced. Moreover, the process clearance to be left when the discrete coupled inductor is arranged on the system board can be narrowed, and the size and footprint can be reduced.

FIG.26is an improvement on the basis ofFIG.25, in which the pillars that are adjacent to any two coupled inductors have been canceled, leaving magnetic loop multiplexing to other remaining pillars. Specifically, inFIG.26, the passages32and33inFIG.25are merged into one passage, and so are the passages34and35inFIG.26. The left-to-right dimension of the multi-phase integrated inductor is further reduced, and so is its size.

FIG.27is an improvement on the basis ofFIG.25, in which the left and right side pillars of the multi-phase integrated inductor are canceled to reduce the size and footprint of the inductor, leaving magnetic loop multiplexing to other remaining pillars.

FIG.28is an improvement on the basis ofFIG.25, in which all pillars without windings are canceled, leaving only the pillars12,14and16inFIG.28. Two-phase windings are respectively arranged on the pillars12,14and16, and a multi-phase coupled inductor is formed by mutual magnetic loop multiplexing, thereby further reducing the size and footprint of the inductor.

FIG.29offers a schematic structural view showing formation of a stacked power supply module based on the coupled inductor proposed in the present disclosure. The two-phase parallel buck circuit shown inFIG.30ais described. The parallel operation of the two-phase buck circuit is realized by the chip8packaged in the insulating packaging material9at the bottom. The two-phase buck main circuit may be implemented by a package of a plurality of chips8or a single chip8. The conductive legs71and72are electrically connected to a middle point SW1of a first switching cell and a middle point SW2of a second switching cell of the chip8, respectively. A plurality of input capacitors10may also be arranged above or within the package, the pins of which are electrically coupled to the Vin and GND pins inFIG.30a.

The winding22a1of the coupled inductor in the upper part ofFIG.29is electrically connected to the conductive leg71, and the winding21a1is electrically connected to the conductive leg72. The winding22a1and the winding22a2are electrically connected to the winding22b, and the winding21a2and the winding21a1are electrically connected to the winding21b. By arranging the windings21aand22bto cross with each other outside the passage, the same type terminals of the windings (i.e., the winding21a1and the winding22a1) can be distributed on the same side of the inductor, serving as two input terminals that are electrically connected to the first switching cell and the second switching cell, respectively. The windings21a2and22a2are electrically connected to the conductive leg73. The conductive member73may form a pad (not shown) at the bottom of the package to form an external output terminal for the overall power module.

Of course, the winding22a1inFIG.29can also be directly and electrically connected to the pad, which in turn is electrically connected to the SW1, on the surface of the package chip module9, and the winding21a1can be directly connected to the pad, which in turn is electrically connected to the SW2, on the surface of the package chip module9, eliminating the conductive legs71and72. The windings21a2and22a2can be directly and electrically connected to the pad, which in turn is electrically connected to the output terminals, on the surface of the package insulator1, eliminating the copper block73. In this embodiment, a complete power module has been structured on the basis of the foregoing various coupled inductors. The SW terminals are drawn from the upper side of the package of the chip8, and then upward to be electrically connected with the windings21a1and22a1of the inductor. Then output currents are drawn out from the same side of the module through the crossing of the first windings22band21b, and then through the windings21a2and22a2. The two-phase output currents of the overall module are drawn out from the same side, which is convenient for customer application, and good for the symmetry of the two-phase circuit. In addition, most of the power current of the overall module flows in the vertical direction, offering short current path, small impedance and desirable heat dissipation towards upwards and downwards. The overall assembly is easy to install, compact in structure and high in power density.

FIGS.30ato30cillustrate some of the application circuits of the present disclosure, but the applications are not limited to these circuits.FIG.30aillustrates a buck circuit in which Cin represents an input capacitor, Co represents an output capacitor, Vin represents the positive input of the power supply module, GND represents the negative input of the power supply module, Vo represents the positive output of the power supply module, SW1represents the midpoint of the first switching cell, SW2represents the midpoint of the second switching cell, where SW1and SW2are electrically connected to the input terminals (i.e., a dotted terminal of the first winding and a non-dotted terminal of the second winding) of the coupled inductor, and V1represents a positive output voltage of the power supply module having an output voltage different from that of Vo.FIG.30billustrates a Boost circuit.FIG.30cillustrates a Buck/Boost circuit. Although the power supply module has been described above by taking the multi-phase parallel operation of the circuit shown inFIG.30aas an example, the coupled inductor of the present disclosure can also be applied in other circuit topologies. For example, other circuits may include, but not limited to, the inversely coupled inductors in the circuits such as Cuk, flyback, switch capacitor, LLC and the like. By referring to similar design and analysis, it is possible to achieve similar performance and effect improvements.

Further,FIG.31ashows a structure of a power supply module. As shown inFIG.31a, a packaged chip module1003, a coupled inductor1005(by way of example rather than limitation, an inversely coupled inductor) and a heatsink1007are stacked in the same order on the main board1001. Thus, the heat, which is primarily generated by the packaged chip module1003encapsulating multiple switching cells, can be conducted via the coupled inductor1005to, and be dispersed by, the heatsink1007, thereby ensuring normal operation of the packaged chip module1003. However, since the coupled inductor1005in a power supply module structured as such has to conduct the heat, this type of indirect conduction of heat also poses a more stringent challenge to the design of the heat dissipation.

For the purpose of avoiding the defect in the structure shown inFIG.31a,FIGS.31bto31dprovide another power supply module structure that can improve the heat dissipation performance for the power supply module. As shown inFIGS.31bto31d, a coupled inductor1005, a packaged chip module1003(which includes switching cells10031and10033) and a heatsink1007are stacked in the same order on the main board1001, so that the heat generated by the packaged chip module1003can be immediately dispersed via the heatsink1007, thereby ensuring the normal operation of the packaged chip module1003.

Since the coupled inductor inFIG.31candFIG.31dare of a conventional type in that all lead out pins are on the same end face, extra connecting wires (e.g., the black thick solid lines indicated by Pin1inFIG.31cand Pin2inFIG.31d) are needed to realize the connection between the switching cells and the inductor, or the connection between the lead out pin of the inductor and the output terminal of the module.

In order to reduce the wires (e.g., the black thick solid lines indicated by Pin1and Pin2in the drawings), so as to reduce direct current (DC) impedance and improve space utilization, the lead out pins of the coupled inductor1005are arranged on two end faces of the inductor, with a dotted terminal of the first winding and a non-dotted terminal of the second winding being arranged on the same end face of the coupled inductor1005, as shown inFIG.31b.

Specifically, the coupled inductor provided in the present embodiment includes a magnetic core (e.g., a flat type magnetic core), a first winding (e.g., a one-turn or multi-turn winding) and a second winding (e.g., a one-turn or multi-turn winding). The magnetic core includes a first end face and a second end face, which are oppositely arranged. A first passage and a second passage are formed, which extend along a first direction and are arranged in parallel, penetrating through the first end face and the second end face. The first winding passes through the first passage for a number of times less by one than that of through the second passage. The second winding passes through the second passage for a number of times less by one than that of through the first passage, and the second winding passes through the second passage for a number of times equal to that of the first winding passing through the first passage. Two terminals of the first winding serve as the first terminal and second terminal of the coupled inductor, respectively, and two terminals of the second winding serve as the third terminal and fourth terminal of the coupled inductor, respectively. The first and third terminals of the coupled inductor are located on the first end face, and the second and fourth terminals of the coupled inductor are located on the second end face. Additionally, two terminals located on the same end face are one dotted terminal of the first winding and one non-dotted terminal of the second winding.

For example, the coupled inductor may be a hexahedron structure whose length and width are both larger than the height. Specifically, the coupled inductor includes a top end face, a bottom end face, a left side face, a right side face, a front side face and a rear side face. The coupled inductor is provided with a left passage and a right passage, both of which extend along the height direction and are arranged in parallel, and the left and right passage both penetrates the top end face and the bottom end face. A front winding and a rear winding are arranged in parallel in the left and right passage. The front winding runs through the left passage by one time and through the right passage by two times, while the rear winding runs through the left passage by two times and through the right passage by one time. The two terminals of the front winding and the rear winding are separately located on two end faces, i.e., the top end face and the bottom end face. The top terminal and bottom terminal of the front winding serve as the first terminal and the second terminal of the coupled inductor, respectively, the top terminal and bottom terminal of the rear winding serve as the third terminal and the fourth terminal of the coupled inductor, respectively. Additionally, one of the top terminal of the front winding and the top terminal of the rear winding is a dotted terminal while the other is a non-dotted terminal.

In a specific application, the first terminal of the first winding is connected to the first switching cell, the third terminal of the second winding is connected to the second switching cell, while the second terminal of the first winding and the fourth terminal of the second winding serve as the output for the power supply module. For the purpose of facilitating connection works, optionally, the first to fourth terminals of the first and second windings include first to fourth pads for electrical connections, where the first to fourth pads are used to be soldered to the main board, the packaged chip module, etc., respectively.

In the coupled inductor of this embodiment, the input/output pins are located separately on the top end face and bottom end face, eliminating the need for any extra pin or wire in realizing the electrical connection for the packaged chip module, the coupled inductor and the main board, which is advantageous in reducing the DC impedance and optimizing the space utilization for the power supply module.

Of course, in some examples, the dotted and non-dotted terminals of the coupled inductor in the power supply module may also be arranged on the opposite end faces of the coupled inductor, with electrical connections among various components by increasing the length of the connecting wires or including extra pins in the packaged chip module, as shown inFIG.31candFIG.31d.

Now, several specific structures that can fulfill the requirements of the coupled inductor inFIG.31bwill be briefly introduced. However, it should be understood that the following specific implementations are not specific limitations on the present disclosure. For instance, the inversely coupled inductor shown inFIG.9can equally fulfill the above inventive concept. Therefore, subject to the above inventive concept, those skilled can freely replace any feature in various embodiments, or freely recombine features from different embodiments.

FIG.32ashows an illustrative structure of a coupled inductor,FIG.32bis an exploded view of the coupled inductor, andFIG.32cis a top view ofFIG.32a. The coupled inductor1005shown inFIG.32atoFIG.32cdiffers from the inversely coupled inductor shown inFIG.9andFIG.10by that the first winding21and the second winding22of the coupled inductor1005inFIG.32ado not intersect, which helps the coupled inductor1005to cut size in the height direction, improving applicability to occasions where low-profile is required. Additionally, insulation is not necessary between the first winding21and the second winding22, simplifying the fabrication work.

Specifically, as shown inFIG.32atoFIG.32c, the coupled inductor1005includes: a magnetic core1, a first winding21and a second winding22. The magnetic core1includes three pillars, i.e., pillars11to13, where two side legs10and the pillars11and12form the first passage31, and the two side legs10and the pillars12and13form a second passage32. That is, the magnetic core forms an “8” shaped magnetic loop. In some embodiments, the magnetic core may also be an “E” shaped magnetic core. The first passage31and the second passage32have two opposite end faces, namely a first end face39aof the passage and a second end face39bof the passage.

The magnetic core material that the magnetic core1is made from may be dust type core material with distributed air gaps, such as iron dust core, alloy dust core, amorphous dust core, nano-crystalline dust core, etc., or a combination thereof, which have low magnetic permeability, typically below200.

The first winding21includes a first portion211, a second portion212, a third portion213, a fourth portion214joining the first portion and the second portion, and a fifth portion215joining the second portion and the third portion. The second winding22includes a first portion221, a second portion222, a third portion223, a fourth portion224joining the first portion and the second portion, and a fifth portion225joining the second portion and the third portion.

The second portion212of the first winding21, the first portion221of the second winding22and the third portion223of the second winding22all penetrate the first passage31. The first portion211of the first winding21, the third portion213of the first winding21and the second portion222of the second winding22all penetrate the second passage32.

The fifth portion215of the first winding21and the fifth portion225of the second winding22are both on the side of the first end face39aoutside the passage, respectively realizing electrical connections between the second portion212and the third portion213of the first winding21, and between the second portion222and the third portion223of the second winding22. The fourth portion214of the first winding21and the fourth portion224of the second winding22are both on the side of the second end face39boutside the passage, respectively realizing electrical connections between the first portion211and the second portion212of the first winding21, and between the first portion221and the second portion222of the second winding22.

That is, the first winding21runs through the first passage31for one time and through the second passage32for two times, while the second winding22runs through the first passage31for two times and through the second passage32for one time. Of course, in some embodiments, the first winding and the second winding may also run through the first and second passages for more times, as long as the first winding runs through the first passage for N times and through the second passage for N+1 times while the second winding runs through the first passage for N+1 times and through the second passage for N times, where N is a natural number greater than or equal to one.

As shown inFIG.32b, a pad (351) is formed at the first portion211of the first winding21in the first end face39aoutside the passage, and the first portion211serves as a first input terminal for the coupled inductor and is connected to the SW1. A pad (353) is also formed at the first portion221of the second winding in the first end face39aoutside the passage, and the first portion221serves as a second input terminal for the coupled inductor and is connected to the SW2. Thus, both input terminals SW1and SW2of the coupled inductor are provided in the same face39a. A pad (352) is formed at the third portion213of the first winding in the second end face39boutside the passage, and the third portion213serves as a first output terminal for the coupled inductor and is connected to the Vo. A pad054) is also formed at the third portion223of the second winding in the second end face39boutside the passage, and the third portion223serves as a second output terminal for the coupled inductor and is connected to the Vo. Thus, both output terminals Vo of the coupled inductor are also provided in the same face39b. Since the first end face39aand the second end face39bare opposite faces, the two pads of the same winding are provided in different faces. When a current flows from SW1and SW2to Vo, the first winding and the second winding have opposite current directions in the first passage31, as well as in the second passage32. Thus, the first winding and the second winding create in the magnetic core magnetic fluxes that are in opposite directions and cancel out each other. That is, when SW1and SW2are provided in the same face as inputs, one of the pad (351) where SW1is located and the pad (353) where SW2is located is a dotted terminal for the coupled inductor while the other is a non-dotted terminal. That is, a dotted and a non-dotted terminal are provided in the same end face for the coupled inductor in this embodiment. It should be understood that this embodiment does not limit any other aspect such as the size, shape or material of the pads.

As shown inFIG.32bandFIG.32c, the arrows in the figures indicate the directions in which the electric currents flow through the first winding21and the second winding22, i.e., from SW1to Vo and from SW2to Vo. Since the currents in the first winding21and the second winding22encircling the pillar12of the magnetic core are in opposite directions, the magnetic fluxes in the pillar created by the first winding21and the second winding22cancel out each other.

Reference is made to bothFIG.32dandFIG.32e, which are a sectional view and a distribution of magnetic flux along location A-A′ of the coupled inductor inFIG.32a. InFIG.32d, dotted lines with arrows represent the distribution of magnetic flux of the first winding21, Φ21A and Φ21B are main magnetic fluxes of the first winding21, and Φ21c, Φ21d, Φ21eand Φ21fare leakage magnetic fluxes of the first winding. The main magnetic fluxes are defined as magnetic fluxes of the first winding that are coupled with the second winding, and the leakage magnetic fluxes are defined as magnetic fluxes of the first winding that are not coupled with the second winding. InFIG.32e, dotted lines with arrows represent the distribution of magnetic flux of the second winding22, Φ22A and Φ22B are main magnetic fluxes of the second winding22, and Φ22c, Φ22d, Φ22eand Φ22fare leakage magnetic fluxes of the second winding. As can be known with reference toFIG.32dandFIG.32e, the main magnetic fluxes Φ21A and Φ21B inFIG.32dare in an opposite direction of, and cancels out, the main magnetic fluxes Φ22A and Φ22B inFIG.32e.

In this embodiment, as shown inFIG.32ctoFIG.32e, the magnitudes of the leakage magnetic fluxes Φ21c, Φ21d, Φ21eand Φ21fof the first winding21are associated with: a spacing t between the third portion213of the first winding and the second portion222of the second winding22; a spacing t between the second portion212of the first winding and the third portion223of the second winding; a width d of the first passage31of the magnetic core; and a width d of the second passage32. Assuming the size of d remains unchanged, then a larger spacing t leads to a larger leakage inductance and a weaker coupling, while a smaller spacing t leads to a smaller leakage inductance and a stronger coupling. For the same reason, assuming the size of the spacing t remains unchanged, and then a larger passage width d leads to a smaller leakage inductance and a stronger coupling, while a smaller passage width d leads to a larger leakage inductance and a weaker coupling. The altering and toning of the leakage magnetic fluxes Φ22c, Φ22d, Φ22eand Φ22fof the second winding22is similar to those for the leakage magnetic flux of the first winding21, which will not be repeated herein.

FIG.32fillustrates an optional fabricating method for the coupled inductor inFIG.32a. As shown inFIG.32f, the magnetic core1is integrally formed from dust type core material with distributed air gaps. Then, the second portion212of the first winding, the first portion221and the third portion223of the second winding are assembled in the first passage31of the magnetic core1. The first portion211and the third portion213of the first winding and the second portion222of the second winding are assembled in the second passage32of the magnetic core1. Then, the portions214and215, which join the first portion, second portion and third portion of the first winding21, are assembled, e.g., by means of soldering, and the portions224and225, which join the first portion, second portion and third portion of the second winding22, are assembled by means of soldering, etc.

In some examples, the coupled inductor inFIG.32amay also be fabricated using the following: integrally forming the first to third portions of the first winding21, the first to third portions of the second winding22, and the magnetic core1with distributed air gaps together, and then combining the portions214and215, which join the first to third portions of the first winding21, and the portions224and225, which join the first to third portions of the second winding22, by means such as soldering.

FIG.33aillustrates an exemplary structure of another coupled inductor.FIG.33bis an exploded view of the inversely coupled inductor shown inFIG.33a,FIG.33cis a top view of theFIG.33a,FIG.33dandFIG.33eare a sectional view and a distribution diagram of magnetic fluxes along location A-A′ ofFIG.33a. The coupled inductor of this embodiment differs from the coupled inductor1005inFIG.32aby the interleaving between the first winding21and the second winding22of the coupled inductor of this embodiment, which is intended to further reduce the leakage inductance and enhance the coupling.

Specifically, as compared withFIG.32b, the second portion212of the first winding inFIG.33bhas swapped position with the third portion223of the second winding, and the third portion213of the first winding21has swapped position with the second portion222of the second winding22. Correspondingly, the fourth and fifth portions214,215,224and225, which join the first, second and third portions of the windings, have also been re-deployed.

As shown inFIGS.33dto33e, the magnetic flux paths have become somewhat different as the windings have changed places. Referring toFIG.33d, the main magnetic fluxes Φ21A and Φ21B of the first winding21are distributed identically as the main magnetic fluxes of the first winding21inFIG.32c. In this embodiment, Φ21c, Φ21eand Φ21fare leakage magnetic fluxes of the first winding21. The magnetic flux Φ21din this embodiment belongs to the main magnetic flux between the first portion of the first winding21and the second portion of the second winding. It should be noted in this embodiment that the main magnetic fluxes between the second portion of the first winding21and the first and third portions of the second winding22, as well as the third portion of the first winding21and the second portion of the second winding22, are not shown.

Referring toFIG.33e, the main magnetic fluxes Φ22A and Φ22B of the second winding22are also distributed identically as the main magnetic fluxes of the second winding22inFIG.32c. In this embodiment, Φ22c, Φ22eand Φ22fare leakage magnetic fluxes of the second winding22. The magnetic flux Φ22din this embodiment belongs to the main magnetic flux between the first portion of the second winding and the second portion of the first winding. For the same reason, in this embodiment, the main magnetic fluxes between the second portion of the second winding22and the first and third portions of the first winding21, as well as the third portion of the second winding22and the second portion of the first winding21, are not shown. In this embodiment, the magnitude of the leakage inductance is toned in the same way as the coupled inductor inFIG.32a, so is the fabricating process of the coupled inductor, none of which will be repeated herein.

In this embodiment, as can be seen inFIG.33c, the projection of the first winding21crosses with that of the second winding22. For example, the projections on the top view by the fourth portion214of the first winding21and the fifth portion225of the second winding22intersect cross with each other, so do the fourth portion224of the second winding22and the fifth portion215of the first winding21. By configuring the first winding21and the second winding22to intersect at their projections, vertical dimension is reduced, the need for insulation between the windings is also eliminated. Meanwhile, due to the intersection between the windings, the leakage inductance is further reduced, while the coupling is enhanced, allowing the coupled inductor to create an even smaller dynamic inductance, thereby improving the dynamic performance of the power supply module.

FIG.34aillustrates an illustrative structure of another coupled inductor,FIG.34bis an exploded view of the inversely coupled inductor inFIG.34a, andFIG.34cis a top view along location A-A′ ofFIG.34a. As shown inFIG.34atoFIG.34c, the coupled inductor of this embodiment differs from the coupled inductor1005inFIG.32ain that: in the first passage31of the magnetic core1, a magnetic material52is filled between the second portion212of the first winding21and the third portion223of the second winding22, and a magnetic material53is filled between the third portion223of the second winding22and the first portion221of the second winding22. For the same reason, in the second passage32of the magnetic core1, a magnetic material51is filled between the first portion211of the first winding21and the third portion213of the first winding21, and a magnetic material54is filled between the third portion213of the first winding21and the second portion222of the second winding22. It should be understood that the relative permeability of the magnetic materials51,52,53and54may be the same as or less than that of the magnetic material(s) of the magnetic core1.

The magnetic flux distribution of this embodiment is the same as that of the coupled inductor inFIG.32a, hence the leakage inductance may also be adjusted in the same way as shown inFIG.34c, i.e., by adjusting the width d of the first passage31or the second passage32, or the spacing t between the windings in the passage. Of course, the leakage inductance may also be adjusted by adjusting the relative permeability of the magnetic materials51,52,53and54in the first passage31and the second passage32. This embodiment provides a more flexible adjustment for the leakage inductance that better fulfills the demand for variety in the leakage inductance.

FIG.35aillustrates an illustrative structure of still another coupled inductor,FIG.35bis an exploded view of the coupled inductor inFIG.35a, andFIG.35cis a top view along location A-A′ ofFIG.35a. As shown inFIGS.35ato35c, the coupled inductor of this embodiment differs from the coupled inductor inFIG.34ain that: the portions of the first winding21and the second winding22located in the passages31and32are formed as cylinders, i.e., the first portion211, second portion212and third portion213of the first winding and the first portion221, second portion222and third portion223of the second winding are formed as cylinders.

According to the coupled inductor of this embodiment, the portions of the windings21and22in the passages31and32are cylinders instead of rectangular prisms, allowing for more magnetic materials to be filled into the passages31and32, thereby increasing the bulk of the magnetic materials to reduce the loss of the magnetic core. Thus, the overall loss of the coupled inductor can be reduced without altering the DC impedance of the winding. Assuming the inductance remains unchanged, the systematic loss can be reduced, thereby improving the efficiency.

Similarly, the coupled inductor of this embodiment has the same distribution of magnetic flux and the manner for adjusting the leakage inductance as the coupled inductor inFIG.34a.

FIG.36aillustrates an illustrative structure of another coupled inductor, andFIG.36bis a sectional view along location A-A′ ofFIG.36a. As shown inFIG.36aandFIG.36b, the coupled inductor of this embodiment differs from the coupled inductor inFIG.35ain that: the coupled inductor of this embodiment is provided on the two side legs10of the magnetic core1with four air gaps61,62,63and64; the magnetic materials52and53filled in the first passage31are provided with air gaps72and74, and the magnetic materials51and54filled in the second passage32are provided with air gaps71and73, where the magnetic materials51-54have high relative magnetic permeability of over200, and may be of, e.g., ferrite. With the magnetic materials with high magnetic permeability, the leakage inductance and the coupling have a wider range of adjustment, enabling the coupled inductor to be applied in a wider frequency range. Meanwhile, since the air gaps are configured as such, the coupled inductor can also have improved saturation current properties.

The magnetic flux distribution of the coupled inductor in this embodiment is the same as that of the coupled inductor inFIG.32a. The air gaps61,62,63and64on the side legs are used for adjusting the main magnetic fluxes, i.e., for adjusting the magnitude of the self-inductance. The air gaps71,72,73and74in the passages are used for adjusting the leakage magnetic fluxes, i.e., for adjusting the magnitude of the leakage inductance. By combining the usage of the air gaps61to64and71to74, the leakage inductance and the coupling can be flexibly adjusted.

It should be noted that the magnetic materials with high magnetic permeability are not suitable for integral forming processes, and hence the inversely coupled inductor of this embodiment is adapted to assembling process. Moreover, the presence of the air gaps means the magnetic core may be split into three, which is also convenient in the assembling work.

FIG.37aillustrates an illustrative structure of another coupled inductor,FIG.37bis an exploded view of the coupled inductor inFIG.37a, andFIG.37cis a schematic assembling diagram for the coupled inductor inFIG.37a. As shown inFIG.37atoFIG.37c, the coupled inductor of this embodiment differs from the coupled inductor1005inFIG.32ain that: the coupled inductor of this embodiment is provided with three air gaps41,42and43on the three pillars11,12and13of the magnetic core1; meanwhile, the magnetic core1is made from a magnetic material having high relative magnetic permeability of over200, e.g., ferrite. In this embodiment, the air gaps41and43have to be provided, while the air gap42may or may not be provided.

As shown inFIG.37c, the magnetic core1is divided by the air gaps41,42and43into two “E”-type magnetic cores. The windings21and22are pre-fabricated into the shape as shown inFIG.37c, and are pre-sleeved over the “E”-type magnetic cores. Then, the two “E”-type magnetic cores are combined with each other, with a proper control of the size of the air gaps, accomplishing the assembling.

In this embodiment, the coupled inductor has the same magnetic flux distribution as that of the coupled inductor inFIG.32a. In this embodiment, the leakage inductance is adjusted by means including adjusting the spacing t between the windings in the passage, adjusting the width d of the passages. The air gaps41,42and43may also be used in adjusting the leakage inductance and the self-inductance.

The coupled inductor of this embodiment has a simple structure as well as fabrication process, with flexibility in the adjustment, facilitating mass production.

FIG.38aillustrates an illustrative structure of another coupled inductor, andFIG.38bis a top view of the coupled inductor shown inFIG.38a. As shown inFIG.38aandFIG.38b, the coupled inductor of this embodiment differs from the inversely coupled inductor1005inFIG.32ain that: the coupled inductor of this embodiment also serves as a carrier plate in addition to including the function of an inductor.

Reference is made toFIG.31b, in order to realize electrical connection in that power supply module, a carrier plate or a part similar to a carrier plate (not shown inFIG.31b) is needed between the coupled inductor and the packaged chip module (or IPM module), as well as between the inductor and the main board, for creating a connection. The carrier plate functions to connect the input on the main board to the IPM module, connect the IPM module to the SW pin of the winding of the coupled inductor, and connect the Vo pins of the inductor to the main board. Meanwhile, the carrier plate also includes connections for signal lines. As can be seen by puttingFIG.38atogether withFIG.38b, the magnetic core1, first winding21, second winding22are same as those of the coupled inductor inFIG.32a, except that this embodiments further includes connections for connecting Pins81,82,83and84, etc., which are used for power lines, e.g., input voltage, output voltage, GND, etc. Additionally, connections are further included for connecting Pins91,92,93,94,95,96,97, etc., which are used for signal lines. The power Pin and the signal Pin may be adjusted as needed by those skilled in terms of dimensions, quantities and configurations, which are not limited to the cases shown inFIG.38aandFIG.38b.

In this embodiment, the features of the coupled inductor itself are no different from the coupled inductor inFIG.32a. However, since the connection Pins are integrated into the inversely coupled inductor of this embodiment, the space surrounding the inductor, which had been conserved for making connections, can be utilized to expand the size of the inductor, i.e., to expand the size of the inductor magnetic core and windings, thereby reducing the loss for the inductor. Meanwhile, after the connection Pins have been integrated into the inductor, the fabricating process of the modular power can become simpler, effectively lowering the cost.

FIG.39aillustrates an illustrative structure of another coupled inductor,FIG.39bis a perspective view of the magnetic core and part of the windings of the coupled inductor inFIG.39a, andFIG.39cis a perspective view for the coupled inductor shown inFIG.39a. As shown inFIG.39atoFIG.39c, the coupled inductor of this embodiment differs from the coupled inductor inFIG.32ain that: the winding of the coupled inductor of this embodiment is fabricated using a method different from that of the coupled inductor inFIG.32a. Specifically, the windings in this embodiment are fabricated using a printed circuit board printing process (PCB trace).

As shown inFIG.39aandFIG.39c, where100indicates a PCB substrate, the magnetic core1, first portion211of the first winding21, second portion212of the first winding21, third portion213of the first winding21, first portion221of the second winding22, second portion222of the second winding22, and third portion223of the second winding22as shown inFIG.39bare embedded within the PCB substrate100. Then, with the PCB process, PCB traces are fabricated as the fourth portion214and fifth portion215of the first winding, and the fourth portion224and fifth portion225of the second winding. Then, a PCB printing process is used to fabricate, e.g., the via-hole110, etc., inFIG.39c, so as to use the via-hole110, etc., to join various parts of the windings, making the windings in this embodiment to have the same winding structure inFIG.32a.

By using the PCB printing process in this embodiment to fabricate the coupled inductor, the operation can be simple, and the PCB substrate can, in addition to embedding the coupled inductor, contain the power Pins and signal Pins, which are needed in the power supply module ofFIG.31, in the form of via-holes provided in the PCB substrate. In addition, as long as the current density falls within the requirement, the first portion211, second portion212and third portion213of the first winding21and the first portion221, second portion222and third portion223of the second winding22may all be substituted by via-holes in the PCB. That is, all that is needed is to bury within the PCB the magnetic core1having the first passage31and the second passage32, and various portions of the first winding21and the second winding22can be implemented using the PCB printing process. Of course, the coupled inductors inFIG.34aandFIG.35amay also be embedded within the PCB. For example, a magnetic core1without any passage may be embedded within the PCB substrate100, and when the PCB printing process is used to fabricate the first portion211to third portion213of the first winding21and the first portion221to third portion223of the second winding22, one may simply create holes on the magnetic core1and then fabricate the via-holes as the windings.

Other features of the coupled inductor of this embodiment are same as those of the coupled inductor1005ofFIG.32a, which will not be repeated herein.

FIG.40aillustrates a four-phase coupled inductor created by combining two coupled inductors1005ofFIG.32a. There is no coupling or very weak coupling between the two coupled inductors1005. Similarly,FIG.40billustrates a six-phase coupled inductor created by combining three coupled inductors1005ofFIG.32a. Of course, there is no coupling or very weak coupling among the three coupled inductors1005.FIG.40cillustrates an eight-phase coupled inductor created by combining four coupled inductors1005ofFIG.32a. Still, there is no coupling or very weak coupling among the four coupled inductors1005. It can be appreciated that the coupled inductors of any of the foregoing embodiments may be combined into a multi-phase coupled inductor. A multi-phase coupled inductor may be joined with an integrated multi-phase power chip module to form a multi-phase power supply module to provide higher power output. Compared with discrete two-phase power supply modules, a multi-phase integrated power supply module can further conserve space on the main board.

Power density is also increased.