INTEGRATED COUPLED INDUCTOR BASED ON COMPOSITE MATERIAL AND MULTI-PHASE VRM APPLYING THE SAME

An integrated coupled inductor based on a composite material and a multi-phase VRM applying the integrated coupled inductor are provided. The integrated coupled inductor comprises an inductor assembly and a connector, wherein the inductor assembly comprises a magnetically permeable core and at least two windings; the magnetically permeable core comprises a first magnetically permeable core and a second magnetically permeable core; the first magnetically permeable core is made of a first magnetic material; the second magnetically permeable core is made of a second magnetic material; and the permeability of the second magnetic material is lower than that of the first magnetic material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 202310135410.6 filed on Feb. 19, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The invention relates to a high-frequency power supply, in particular to an integrated coupled inductor based on composite material and a multi-phase VRM applying the same.

Description of Related Art

In recent years, with the development of technologies such as data centers, artificial intelligence and supercomputers, more and more functions powerful ASIC are applied, such as a CPU, a GPU, a machine learning accelerator, a network switch, a server and the like, they consume lot of electricity, for example, thousands of amps are achieved, and their electric power demand fluctuates rapidly. The load is traditionally supplied using a multi-phase voltage regulator module (VRM, Voltage Regulator Modules). In order to keep up with the increase in load current and bandwidth, the phase number of the VRM and the capacitance of the output decoupling capacitor of the VRM are increased, and the method improves the transient response of the traditional VRM to a certain extent.

However, due to the factors such as the larger output impedance of the traditional VRM, the space occupied by the decoupling capacitor and the distance between the decoupling capacitor and the load, the performance limit is achieved in the aspect of transient response. Other techniques to improve traditional VRM, such as increasing switching frequency and/or reducing inductance values, improving transient response, but at the expense of efficiency reduction. The anti-coupled technology has relatively lower leakage inductance, so that the anti-coupled inductor has relatively faster transient response; meanwhile, the anti-coupled inductor has a higher steady-state equivalent inductance, which is beneficial to improve efficiency; i.e., the anti-coupled technology can both meet the requirement for transient performance and also allow for increase in efficiency, so that the anti-coupled technology is a hot spot designed by a VRM. However, with advances in semiconductor technology and increasing current ratings of switching devices, in order to meet demands of increasing power densities of VRM, volume of inductor in VRM needs to be further reduced with increasing power density, i.e. The challenges are small volume, large steady state inductance, small dynamic inductance, high saturation current and low losses.

The coupled inductor in the prior art mainly applies a ferrite material with high permeability, which have good coupled characteristic, low loss, low cost, but low saturation magnetic flux density, which cannot meet the inductance requirements of the VRM inductor under the large direct current bias, and under the condition that the two phases are unbalanced, the magnetically permeable core is easy to saturate, so that the switching device is directly connected, and make the VRM failure. In the prior art, a low-permeability powder core material is also used for manufacturing a coupled inductor, which have good saturation characteristic of the material, high cost, low permeability, and poor coupled characteristic; and along with the improvement of the frequency, the loss of the powder core material is rapidly increased, and the characteristics of the coupled inductor cannot be fully exerted.

SUMMARY

In general, one aspect features an integrated coupled inductor based on the composite material comprising:an inductor assembly and a connector;wherein the inductor assembly comprises a magnetically permeable core and at least two windings;wherein the magnetically permeable core comprises a first magnetically permeable core and a second magnetically permeable core;wherein the first magnetically permeable core comprises at least two magnetic columns and at least two cover plates, and the at least two magnetic columns are arranged between the at least two cover plates;wherein the first magnetically permeable core is made of a first magnetic material;wherein the second magnetically permeable core is arranged between two adjacent magnetic columns or on the side surface of the first magnetically permeable core;wherein the second magnetically permeable core is made of a second magnetic material;wherein the permeability of the second magnetic material is lower than that of the first magnetic material;wherein each winding is wound on at least one magnetic column corresponding to the winding;wherein the winding comprises a first bonding pad and a second bonding pad, the first bonding pad is arranged on the top surface of the inductor assembly, and the second bonding pad is arranged on the bottom surface of the inductor assembly;wherein the connector comprises a power connector and a signal connector; the power connector and the signal connector are arranged on the outer side surface of the inductor assembly respectively;wherein the power connector is used for transmitting power current between the top surface and the bottom surface of the inductor assembly; the power connector comprises a power Vin and a power GND;wherein the signal connector is used for transmitting a signal current between the top surface and the bottom surface of the inductor assembly.

Optionally, in the working process of the integrated coupled inductor, the magnetic fluxes generated by the current in the windings are mutually counteracted in the first magnetically permeable core; and the magnetic fluxes generated by the current in the windings are mutually enhanced in the second magnetically permeable core.

Optionally, the relative permeability of the first magnetic material is higher than 200; and the relative permeability of the second magnetic material is lower than 200.

Optionally, at least two pairs of power Vin and power GND are provided, each pair of power Vin and power GND are respectively arranged side by side on one side surface of the magnetically permeable core, and the signal connector is arranged on one side surface of the magnetically permeable core which is not provided with the power Vin and the power GND; a metal shielding layer is arranged between the connector and the magnetically permeable core, and the connector and the metal shielding layer are electrically isolated.

Optionally, the connector and the second magnetically permeable core are integrally pressed and formed.

Optionally, the connector and the shielding layer are both arranged on at least one PCB assembly, and the at least one PCB assembly and the inductor assembly form the integrated coupled inductor through assembly.

Optionally, the number of the windings is N, and N is greater than 2; the number of the magnetic columns is N, and the magnetic columns are in one-to-one correspondence with the windings;

wherein the second magnetically permeable core is arranged between two adjacent magnetic columns, specifically:

wherein the second magnetically permeable core is N−1, and the magnetic column and the second magnetically permeable core are alternately arranged.

Optionally, a first air gap is formed in the magnetic column, and a second air gap is formed in the second magnetically permeable core; the first air gap is arranged in a symmetrical and unbalanced mode, and/or the second air gap is arranged in a symmetrical and unbalanced mode; the magnetic column and/or the second magnetically permeable core are arranged from one side surface of the inductor assembly to another side surface in a symmetrical mode, and the first air gap and/or the second air gap are sequentially increased from the edge to the center of the inductor assembly; and the first air gap and/or the second air gap which are symmetrical in center are equal in size.

Optionally, the at least two windings are wound on the same magnetic column of the first magnetically permeable core; the second magnetically permeable core is annular or arc-shaped, and the second magnetically permeable core surrounds the at least one magnetic column and is arranged between the at least two windings.

In general, another aspect features a multi-phase VRM comprises:at least one integrated coupled inductor of claims1to9, both the first pad and the second pad being adjacent to a first side surface of the inductor assembly;wherein a top plate comprises an IPM unit and a passive element;wherein a side conductive connector comprises a signal conductive connector and a power conductive connector, and the side conductive connector is arranged on another side surface, different from the first side surface, of the multi-phase VRM;wherein the IPM unit is electrically connected with a first bonding pad of a corresponding winding, and the second bonding pad is used for being electrically connected with a load.

Optionally, the IPM unit is arranged at the position, close to the first side surface, of the top plate, and the IPM unit is arranged in a mode perpendicular to the winding.

Optionally, the passive element comprises an input capacitor, at least two IPM units are provided, and at least a part of the input capacitor is arranged between two adjacent IPM units.

Optionally, the passive element comprises an input capacitor, the number of the IPM units is more than two, and at least a part of the input capacitor is arranged between every two adjacent IPM units.

DESCRIPTION OF THE EMBODIMENTS

The present application discloses various embodiments or examples of implementing the thematic technological schemes mentioned. To simplify the disclosure, specific instances of each element and arrangement are described below. However, these are merely examples and do not limit the scope of protection of this invention. For instance, a first feature recorded subsequently in the specification formed above or on top of a second feature may include an embodiment where the first and second features are formed through direct contact, or it may include an embodiment where additional features are formed between the first and second features, allowing the first and second features not to be directly connected. Additionally, these disclosures may repeat reference numerals and/or letters in different examples. This repetition is for brevity and clarity and does not imply a relationship between the discussed embodiments and/or structures. Furthermore, when a first element is described as being connected or combined with a second element, this includes embodiments where the first and second elements are directly connected or combined with each other, as well as embodiments where one or more intervening elements are introduced to indirectly connect or combine the first and second elements.

FIG.1Ashows a circuit diagram of a multiphase VRM of this embodiment, a complete multi-phase VRM10(here is a two-phase VRM), comprises an IPM unit121, an IPM unit122, an integrated coupled inductor200, a power VIN2301, a power VIN2302, a power GND2401, a power GND2402, an input capacitor1301, a signal conductive connector270a, and a signal conductive connector270b, wherein each IPM unit comprises two switching devices, a high-end MOSFET and a low-end MOSFET, and the two MOSFETs are connected in series to form a bridge arm; one end of the bridge arm is connected to the positive end of the input power, i.e., the power VIN140; the other end of the bridge arm is connected with the ground end, i.e., the power GND150. The midpoint of bridge arm (the switch point, recorded as SW1212and SW1222) is connected to the input end of the inductor, the output ends of the inductors are connected in parallel or not connected in parallel and then connected with the load to provide energy for the load. The input capacitor1301is used to bypass high frequency switch ripple current to ensure that the input voltage is stable. The signal conductive connector270aand the signal conductive connector270bare respectively used for the transmission of signals such as drive and control of the IPM unit121and the IPM unit122. The integrated coupled inductor200integrates the power VIN2301, the power VIN2302, the power GND2401, the power GND2402, the signal conductive connector270a, and the signal conductive connector270b.

FIG.1Bshows a packaging diagram of a standard IPM unit in the prior art. A connection point SW of the high-end MOSFET and the low-end MOSFET is arranged at one side of the IPM unit, and connection Pads for control signal and the like are arranged at the side opposite to the connection point SW, and the input power connection end VIN and GND are arranged in the middle accordingly.

FIG.2Ais a schematic structural diagram of the two-phase VRM in this embodiment,FIG.2Bis an exploded view,FIG.2Cis a schematic structural diagram of the integrated coupled inductor200inFIG.2B,FIG.2Dis an exploded view of the integrated coupled inductor200,FIG.2Eis a schematic structural diagram of the inductor210inFIG.2D,FIG.2Fis an exploded view of the inductor210coupled inFIG.2E, andFIG.2Gis a cross-sectional view section A-A inFIG.2E. As shown inFIG.2AandFIG.2B, the two-phase VRM comprises a top plate100, an integrated coupled inductor200and a bottom plate300; the top plate100comprises a mainboard PCB110, an IPM unit121, an IPM unit122, an input capacitor1301and other passive element1401; the IPM unit121and the IPM unit122are arranged close to the edge of the mainboard PCB110, since on IPM unit121, the connection points of high-end MOSFET to low-end MOSFET are provided at edge of IPM unit121, and IPM unit121is provided at edge of mainboard PCB110in order to facilitate input end of inductor to be connected directly to SW end of IPM unit121, and to reduce loss of efficiency caused by lateral currents; the other passive element1401mainly a passive element of a control signal loop in the IPM unit121, and a control signal of the IPM unit121is arranged at the other end opposite to the SW, so that the passive element1401needs to be close to the IPM unit121to achieve the effects of good filtering and the like, and therefore the passive element1401is arranged close to the IPM unit; and the input capacitor1301is divided into two parts, one part of the input capacitor1301is arranged at the edge of the other end of the mainboard PCB110and is close to other passive element1401; and one part is arranged between the two IPM units, because the input capacitor1301is closer to the VIN input end of the IPM unit121and the IPM unit122, the better the filtering effect is, and the VIN ends on the IPM unit121and the IPM unit122are arranged on the side close to the control signal.

As shown inFIG.2D, the integrated coupled inductor200comprises a coupled inductor210, a signal conductive connector270, a power conductive connector (comprising a power VIN2301, a power VIN2302and a power GND2401, a power GND2402), a copper sheet2601, a copper sheet2602, an insulating layer2501, and an insulating layer2502. The copper sheets are used to reduce the parasitic inductance of a loop formed by the power Vin and the power GND; the existence of the parasitic inductance will form an oscillation loop with the input capacitor1301, and when the resonance point of the oscillation loop is close to the switching frequency of the switching device, the oscillation amplitude is increased, so that the efficiency of the power circuit is reduced, and a metal layer is added to reduce the parasitic inductance of the power Vin-power GND loop to solve the problem.

The power Vin and the power GND in this embodiment can also be realized through a PCB Trace method, the signal conductive connector270can also be realized in a PCB Trace mode, a copper layer is additionally arranged between the signal conductive connector270and the magnetically permeable core and used for shielding electromagnetic interference, the copper layer can also be connected with the power GND, electric field shielding is achieved, it is ensured that the signal conductive connector270cannot be subjected to electromagnetic interference, and reliable work of the IPM unit121is ensured.

As shown inFIG.2EandFIG.2F, the coupled inductor210comprises a first magnetically permeable core211, a first magnetically permeable core212, a second magnetically permeable core213, a first winding221and a second winding222. In this embodiment, the first magnetically permeable core comprises a cover plate and a magnetic column (i.e., a first magnetic column21aand a second magnetic column21b), and the second magnetically permeable core213is arranged between the first magnetic column21aand the second magnetic column21b; the first winding221is arranged on the first magnetic column21a, and the second winding222is arranged on the second magnetic column21b; and the first winding221is provided with a first bonding pad221aand a second bonding pad221b; and the second winding222is provided with a first bonding pad222aand a second bonding pad222b; the first bonding pad221aand the first bonding pad222aare respectively connected to the SW of the IPM unit; the second bonding pad221band the second bonding pad222bare connected together and then connected to a load; it can be seen fromFIG.2A,FIG.2BandFIG.2Fthat the first bonding pads of the winding are directly and vertically connected to the SW pad of the IPM unit, and no transverse PCB Trace is passed on the mainboard PCB110; therefore, the winding structure can improve the efficiency of the VRM.

As shown inFIG.2G, the magnetic flux generated by the current in the first winding221is a main magnetic flux281and a magnetic flux leakage282; and the magnetic flux generated by the current in the second winding222is a main magnetic flux291and a leakage flux292; the current in the winding flows from the first bonding pad to the second bonding pad, i.e., the current flows to the load from the SW; because of the direction of the main magnetic flux281generated by the current in the first winding is opposite to the direction of the main magnetic flux291generated by the current in the second winding, and the main magnetic flux281and the main magnetic flux291generated by the current in the second winding are mutually counteracted; so, the two-phase inductor in this embodiment works in an anti-coupled state; and because of the leakage flux282generated by the current in the first winding and the leakage flux292generated by the current in the second winding have the same direction in the second magnetically permeable core and the leakage flux282generated by the current in the first winding and the leakage flux292generated by the current in the second winding are mutually enhanced; because of the main magnetic flux281and the main magnetic flux291are mutually counteracted, and the magnetic flux path of the main magnetic flux is mainly the first magnetically permeable core, the saturation stress of the first magnetically permeable core is small, the first magnetic conductive material with the relative permeability higher than 200 can be arranged, and the ferrite material is low in saturation characteristic, high in permeability and low in magnetically permeable core loss density, so that a relatively high coupled coefficient and relatively low magnetically permeable core loss are obtained. The leakage flux282and the leakage flux292are mutually enhanced in the second magnetically permeable core, so that the saturation stress of the second magnetically permeable core is large, and the second magnetically permeable core can be arranged to be a second magnetic conductive material with the relative permeability lower than 200, such as a powder core material with good saturation characteristics, such as an iron powder core, iron silicon, an iron-nickel powder core, an amorphous powder core, a nanocrystalline powder core and the like, so as to obtain a relatively high saturation current.

As shown inFIG.2G, the two magnetic columns of the first magnetically permeable core are provided with a first air gap214; and a second air gap215is provided between the second magnetically permeable core and the first magnetically permeable core (in other embodiments, the air gap may also be an assembly air gap); the first air gap214is used to adjust the size of the main magnetic flux, i.e., the mutual inductance or the coupled coefficient is adjusted; the second air gap215is used to adjust the leakage flux or the leakage inductance; the existence of the air gap can flexibly adjusts the leakage inductance and the mutual inductance according to the application so as to meet different application scenes; and the leakage inductance can be adjusted by adjusting the permeability of the second magnetically permeable core.

FIG.3Ais a schematic structural diagram of a two-phase VRM of this embodiment,FIG.3Bis an exploded view of the integrated coupled inductor200shown inFIG.3A,FIG.3Cis a schematic structural diagram of the coupled inductor210inFIG.3B,FIG.3Dis an exploded view of the inductor210shown inFIG.3C, andFIG.3Eis a cross-sectional view section A-A inFIG.3C. The difference between this embodiment and the Embodiment 1 is that the integrated coupled inductor200and the coupled inductor210in this embodiment are different in structure, as shown inFIG.3B, the integrated coupled inductor200comprises a coupled inductor210, a signal conductive connector270, a power VIN2301, a power VIN2302, a power GND2401and a power GND2402; as shown inFIG.3CandFIG.3D, the coupled inductor210comprises a first magnetically permeable core211, a first magnetically permeable core212, a second magnetically permeable core213a, a second magnetically permeable core213b, a second magnetically permeable core213c, a first winding221and a second winding222; the second magnetically permeable core213a, the second magnetically permeable core213band the second magnetically permeable core213care arranged on the side of the first magnetically permeable core211and the first magnetically permeable core212.

The difference between this embodiment and the Embodiment 1 is that the implementation modes of the connectors (i.e., the power Vin, the power GND and the signal conductive connector270) are different, the connectors and the second magnetically permeable core in this embodiment are integrally pressed and synthesized and sintered together, and then the connectors and the second magnetically permeable core are assembled together with the first magnetically permeable core and the winding.

According to this embodiment, the structure form of the windings and the connection between the windings input end and the SW and the connection between the windings output end and the load are the same as those of the Embodiment 1; thus, the structural arrangement of the windings can improve the efficiency of the VRM;

As shown inFIG.3E, the magnetic flux generated by the current in the first winding221is a main magnetic flux281and a magnetic flux leakage282; and the magnetic flux generated by the current in the second winding222is a main magnetic flux291and a leakage flux292; since the current in the winding flows from the first bonding pad to the second bonding pad, i.e., the current flows to the load from the SW, because of the direction of the main magnetic flux281generated by the current in the first winding is opposite to the direction of the main magnetic flux291generated by the current in the second winding, and the main magnetic flux281and the main magnetic flux291generated by the current in the second winding are mutually counteracted. The two-phase inductor in this embodiment works in an anti-coupled state; the leakage flux282generated by the current in the first winding and the leakage flux292generated by the current in the second winding flow in the second magnetically permeable core, and the leakage flux generated by the current in the first winding mainly flows in the second magnetically permeable core213aclose to the first winding; and the leakage flux generated by the current in the second winding mainly flows in the second magnetically permeable core213bclose to the second winding; and the leakage flux of the first winding and the leakage flux of the second winding are in the same direction in the second magnetically permeable core213c, are mutually enhanced. Since the main magnetic flux281and the main magnetic flux291are mutually counteracted, and the magnetic flux path of the main magnetic flux is mainly the first magnetically permeable core, the saturation stress of the first magnetically permeable core is small, and the first magnetically permeable core can be set to be a ferrite material with low saturation characteristics, high permeability and low magnetically permeable core loss density.

The two magnetic columns of the first magnetically permeable core are provided with a first air gap214; and a second air gap215(which may also be an assembly gap) is provided between the second magnetically permeable core and the first magnetically permeable core; the first air gap214is used to adjust the size of the main magnetic flux, i.e., the mutual inductance or the coupled coefficient is adjusted; the second air gap215is used to adjust the leakage flux or the leakage inductance; the existence of the air gap can flexibly adjust the leakage inductance and the mutual inductance according to the application so as to meet different application scenes; and the leakage inductance can be adjusted by adjusting the permeability of the second magnetically permeable core.

The advantage of this embodiment is that the connector is integrally formed with the second magnetically permeable core, reducing the difficulty of assembling the connector.

FIG.4Ais a schematic structural diagram of a two-phase VRM in this embodiment;FIG.4Bis a schematic structural diagram of a coupled inductor210,FIG.4Cis an exploded view of a coupled inductor210, andFIG.4Dis a cross-sectional view of A-A inFIG.4B. The difference between this embodiment and the Embodiment 1 is that the structure of the coupled inductor210in this embodiment is different, as shown inFIG.4BandFIG.4C, the coupled inductor210comprises a magnetically permeable core (comprising a first magnetically permeable core211, a first magnetically permeable core212and a second magnetically permeable core213), a first winding221and a second winding222. In this embodiment, the first magnetically permeable core comprises a cover plate, a first magnetic column21aand a second magnetic column21b, and the first magnetic column21ais arranged at the central position of the magnetically permeable core; the second magnetically permeable core213is of an annular or segmented arc shape, is arranged around the first magnetic column21aand is arranged between the first winding221and the second winding222; the first winding221and the second winding222are respectively arranged on the first magnetic column21a, and the second magnetic column21bis arranged around a stack formed by the first winding221, the second magnetically permeable core213and the second winding222.

In this embodiment, the connection between the winding input end and the SW and the connection between the winding output end and the load are the same as that of the Embodiment 1; therefore, the structural arrangement of the windings can improve the efficiency of the VRM.

As shown inFIG.4D, the magnetic flux generated by the current in the first winding221is a main magnetic flux281and a magnetic flux leakage282; and the magnetic flux generated by the current in the second winding222is a main magnetic flux291and a leakage flux292; since the current in the winding flows from the first bonding pad to the second bonding pad, i.e., the current flows to the load from the SW, because of the direction of the main magnetic flux281generated by the current in the first winding is opposite to the direction of the main magnetic flux291generated by the current in the second winding, and the main magnetic flux281and the main magnetic flux291generated by the current in the second winding are mutually counteracted. The two-phase inductor in this embodiment works in an anti-coupled state; because of the leakage flux282generated by the current in the first winding and the leakage flux292generated by the current in the second winding have the same direction in the second magnetically permeable core and the leakage flux282generated by the current in the first winding and the leakage flux292generated by the current in the second winding are mutually enhanced. Since the main magnetic flux281and291are mutually counteracted, and the magnetic flux path of the main magnetic flux is mainly the first magnetically permeable core, thus the saturation stress of the first magnetically permeable core is small, and the first magnetically permeable core can be set to be a ferrite material with low saturation characteristic, but high permeability and low magnetically permeable core loss density; a relatively high coupled coefficient and relatively low magnetically permeable core loss are obtained; the magnetic flux leakage flux282and292flow in the second magnetically permeable core, and the directions are the same and are mutually enhanced. Therefore, the saturation stress of the second magnetically permeable core is large, and the second magnetically permeable core can be set as a powder core magnetic material with good saturation characteristics, such as an iron powder core, iron silicon, an iron-nickel powder core, an amorphous powder core, a nanocrystalline powder core and the like; and high saturation current is obtained.

The first magnetic column21ais provided with a first air gap214a, and an assembly air gap214bis provided on the second magnetic column (this embodiment takes an assembled air gap as an example, but the air gap on the second magnetic column is not limited to be an assembled air gap, or may be a second air gap); generally, the first air gap214ais a main air gap, and the first air gap214ais larger than the assembly air gap214b; so that the problem of electromagnetic interference caused by an air gap can be reduced, and the first air gap214acan be arranged to be equal to the size of the assembled air gap214bso as to reduce the alternating current loss of the winding caused by overlarge air gap; and the second magnetically permeable core213is provided with a second magnetically permeable core width21W and a second magnetically permeable core thickness21H; the first air gap214is used to adjust the size of the main magnetic flux, i.e, the mutual inductance or coupled coefficient is adjusted; the second magnetically permeable core width21W and the second magnetically permeable core thickness21H are used to adjust the leakage flux or the leakage inductance; the air gap and the second magnetically permeable core213can be used to flexibly adjust the mutual inductance and leakage inductance so as to meet different application scenes; and the leakage inductance can be adjusted by adjusting the permeability of the second magnetically permeable core213.

This embodiment has the advantages that the mounting mode of the first magnetically permeable core and the second magnetically permeable core is simple, the three side surfaces of the first magnetically permeable core can be used for installing the power PIN and the signal connector, and the magnetic flux leakage cannot generate interference or loss on the power PIN or the signal connector.

FIG.5is a schematic diagram of an application principle of a four-phase VRM; as shown inFIG.5, the four-phase VRM comprises two-phase VRM in parallel, and the input and output of the VRM of the two phases are connected in parallel, so that a four-phase VRM can be formed; the four-phase VRM is formed by integrating the two-phase VRM10aand the two-phase VRM10b; the inductance in the four-phase VRM is also formed by a four-phase integrated coupled inductor; the following embodiments are used for explaining the integration of the four-phase VRM; certainly, the four phases are only one example, and the structure and the method of this invention can be applied to a multi-phase VRM with any more than 2;

FIG.6Ais a schematic structural diagram of the four-phase VRM in this embodiment, andFIG.6Bis an exploded view;FIG.6Cis a schematic structural diagram of the integrated coupled inductor200;FIG.6Dis an exploded view of the integrated coupled inductor200;FIG.6Eis a schematic structural diagram of the coupled inductor210inFIG.6E;FIG.6Fis an exploded view of the coupled inductor210; andFIG.6GandFIG.6Hare cross-sectional views of the section A-A inFIG.6E. As shown inFIG.6AandFIG.6B, the difference between this embodiment and the Embodiment 1 is that this embodiment is a four-phase VRM, but the technical principle is the same as that of the Embodiment 1; and the difference between the embodiment and the Embodiment 1 is that the first air gap214a, the first air gap214b, the first air gap22cand the first air gap214dare arranged in this embodiment.

In this embodiment, the magnetic circuit lengths of the mutual magnetic flux paths between any phase and the other three phases are different, so that the coupled coefficients between any two phases are different; in order to adjust the phenomenon of unequal coupled coefficients caused by unequal lengths of any two-phase magnetic circuits, the mutual coupled consistency between the four-phase inductors is achieved, an unbalanced and symmetrical air gap setting method can be adopted, and the air gap sizes of the first phase and the fourth phase are set to be equal, that is, the sizes of the first air gap214aand the first air gap214dare the same; the sizes of the air gaps of the second phase and the third phase are set to be equal, that is, the size of the first air gap214bis the same as that of the first air gap214c; and the first air gap214band the first air gap214care set to be both larger than the first air gap214aand the first air gap214d, which is an unbalanced setting, in this way, the coupled coefficient balance between any two phases between the four phases can be achieved, the ripple size of the multi-phase output current can be balanced through coupled coefficient balance, and the dynamic performance and efficiency of the VRM can be further improved.

Preferably, in some other multiphase VRMs, the magnetic columns form an array in the direction of the winding forming array, the magnetic columns are sequentially paired in a head-to-tail correspondence relationship, each pair of magnetic columns has a first air gap with the same size, and the size of the first air gap is sequentially increased from the two ends of the array to the middle; the second magnetically permeable cores are sequentially paired in a head-to-tail correspondence relationship, each pair of second magnetically permeable cores has a second air gap with the same size, and the size of the second air gap is sequentially increased from the two ends of the array to the middle.

The leakage flux in this embodiment also has the same problem, and the magnetic circuit lengths of the magnetic flux leakage path and the magnetic flux leakage path between any two phases are different, so that the leakage inductance of each phase is inconsistent; the problem can also be solved by symmetrically unbalanced settings, that is, the second air gap215aon the first magnetic flux leakage path is equal to the second air gap215con the third magnetic flux leakage path and is smaller than the second air gap215bon the second magnetic flux leakage path, and the three-phase leakage inductance can be consistent in size.

FIG.7Ais a schematic structural diagram of a four-phase VRM in this embodiment,FIG.7Bis an exploded view of the integrated coupled inductor200, andFIG.7Cis a schematic structural diagram of the coupled inductor210; andFIG.7EandFIG.7Fare cross-sectional views of the section A-A inFIG.7C. The difference between the embodiment and the embodiment 4, and, the difference between the Embodiment 2 and the Embodiment 1 are the same, that is, the integrated coupled inductor200and the coupled inductor210are different, but the technical effect generated by the integrated coupled inductor200is the same as that of Embodiment 2, and the arrangement mode of the air gap in this embodiment is the same as that of the Embodiment 4.

FIG.7Gis a front view ofFIG.6A, as shown inFIG.7G, first bonding pads221a, first bonding pads222a, first bonding pads223aand first bonding pads224aof the first winding221, the second winding222, the third winding223and the fourth winding224are respectively vertically connected with the IPM unit121, the IPM unit122, the IPM unit123and the IPM unit124; but the input capacitor1301is arranged between the IPM unit121, the IPM unit122, the IPM unit123and the IPM unit124at intervals, so that the first bonding pad of the winding is directly and vertically connected with the SW Pad of the IPM unit, no transverse current exists between the first bonding pad of the winding and the SW Pad of the IPM unit, and the VRM is high in efficiency.

FIG.8Ais a schematic structural diagram of a four-phase VRM in this embodiment, andFIG.8Bis a front view. According to this embodiment, the position of the input capacitor1301is adjusted on the basis of the Embodiment 4. As shown inFIG.8AandFIG.8B, an input capacitor1301is not provided between the IPM unit121and the IPM unit122, an input capacitor1301is not provided between the IPM unit123and the IPM unit124, but the input capacitor1301is provided between every two phases and the edge of the module. In this way, on the premise that the filtering effect of the input capacitor is not affected, the alignment area of the first bonding pad of the winding and the SW pad of the IPM unit is maximized; the welding area of the winding and the SW pad is increased, the impedance between the winding bonding pad and the IPM unit SW is reduced, and the efficiency is improved.

The invention has the following beneficial effects:(1) the ferrite material with high permeability is used for a main magnetic flux path, so that the coupled inductor has good coupled characteristics, the high coupled coefficient allows to achieve a large steady state inductance, to reduce ripple current of the inductance, and to reduce AC loss of the switching device; the ferrite material with a low core loss density is favor to reduce the loss of coupled inductance core;(2) The low-permeability powder core material is used for a flux leakage path, so that the leakage inductance saturation characteristic is good, and the leakage inductance has relatively high saturation current; thus, leakage inductance is still maintained at a certain inductance under large transient load current changes, which can protect the switching device from large current stresses; under the change of the large transient load current, the leakage inductance still maintains a certain inductance, and the switching device can be protected from large current stress;(3) Through symmetrical arrangement of unbalanced air gaps on different phase magnetic columns in the coupled inductor, coupled balance among multiple phases can be realized, coupled equalization is beneficial to reduction of output ripple current, the leakage inductance can be further reduced under the condition that the steady-state inductance is the same, and the dynamic performance of the multi-phase VRM is further improved;(4) One end of the windings is connected to the switching device, and the anther end of the windings is directly connected with the load, so that the current of the power part does not flow transversely, the loss caused by transverse flowing of the power current is eliminated, and the efficiency of the VRM is improved.