CN113674962A

CN113674962A - Four-phase symmetrical reverse coupling magnetic integrated inductor

Info

Publication number: CN113674962A
Application number: CN202111007744.2A
Authority: CN
Inventors: 王来利; 于龙洋; 梁思远; 杨成子; 崔洪昌; 慕伟
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2021-08-30
Filing date: 2021-08-30
Publication date: 2021-11-19

Abstract

The invention discloses a four-phase symmetrical inversely coupled magnetic integrated inductor, comprising an upper end plate, a lower end plate and four magnetic cores, wherein the four magnetic cores are located between the upper end plate and the lower end plate, and the four magnetic cores are The windings are sleeved, the windings on the four magnetic cores are symmetrically distributed, and the inductor has a symmetrical magnetic structure.

Description

Four-phase symmetrical reverse coupling magnetic integrated inductor

Technical Field

The invention relates to an inductor, in particular to a four-phase symmetrical reverse coupling magnetic integrated inductor.

Background

Buck converters with synchronous rectifiers are widely used in portable electronic devices and voltage regulator modules due to their simple circuit structure and control strategy. In recent years, gallium nitride high electron mobility transistors (GaN HEMTs) have proven to be a great advantage in improving the efficiency and power density of DC-DC converters.

The concept of reverse coupled inductors has been successfully applied in interleaved regulator modules based on GaN devices to improve efficiency and power density, while reverse coupled inductors have been demonstrated to reduce iron losses by 40% over direct coupled inductors. With the increasing high performance requirements, multiphase buck converters with synchronous rectifiers are becoming a necessary trend, two-phase buck converters need to be developed into four or more phases. Therefore, the conventional reverse-coupled magnetic structure using EI or EE shaped cores can be used only in the two-phase interleaved buck converter, and is not suitable for three or more phases.

Three-phase and four-phase buck converters have been proposed, which have different inductor parameters due to their asymmetry, resulting in an unbalanced current waveform for the four-phase buck converter; the industry has had a case of using a symmetrical magnetic structure to achieve the back coupling of an N-phase buck converter, although this magnetic structure can achieve the same inductance parameter, as the number of phases increases, the magnetic flux will increase significantly in the center arm, which is not suitable for high power level applications; there is also currently a more symmetric magnetic structure used for four-phase reverse-coupled inductors, but the four inductor parameters are still theoretically different.

Disclosure of Invention

The present invention is directed to overcoming the above-mentioned disadvantages of the prior art and providing a four-phase symmetric reverse-coupled magnetically integrated inductor having a symmetric magnetic structure.

In order to achieve the above purpose, the four-phase symmetric reverse coupling magnetic integrated inductor comprises an upper end plate, a lower end plate and four magnetic cores, wherein the four magnetic cores are positioned between the upper end plate and the lower end plate, the four magnetic cores are respectively sleeved with windings, and the windings on the four magnetic cores are symmetrically distributed.

The winding structure on the four magnetic cores is the same.

And a support column is arranged between every two adjacent magnetic cores.

The number of layers of the winding on the same magnetic core is one.

The number of layers of the winding on the same magnetic core is multiple.

The number of layers of the winding on the same core is determined according to the inductance value of the inductor.

The upper end plate and the lower end plate are both square structures.

Four magnetic cores are evenly distributed along the circumferential direction.

All the support columns are uniformly distributed along the circumferential direction.

The invention has the following beneficial effects:

when the four-phase symmetrical reverse coupling magnetic integrated inductor is in specific operation, the four magnetic cores are positioned between the upper end plate and the lower end plate, the four magnetic cores are respectively sleeved with the windings, and the windings on the four magnetic cores are symmetrically distributed, so that the four-phase symmetrical reverse coupling magnetic integrated inductor has a symmetrical magnetic structure, and the current waveform imbalance of the four-phase buck converter is avoided.

Drawings

FIG. 1 is a topology diagram of a four-phase chopper circuit using reverse-coupled inductors;

FIG. 2 is a graph of inductor voltage and current waveforms at D < 0.25;

FIG. 3 is a schematic structural view of the present invention;

FIG. 4 is a diagram of a magnetic circuit model according to the present invention;

fig. 5 is a PCB winding diagram of the magnetic core 5;

fig. 6 is a structural view of the magnetic core 5;

FIG. 7 is a diagram of a GaN-based prototype plate;

FIG. 8 is a graph of output voltage, high side drive and inductor current for the first phase;

FIG. 9 is a waveform diagram of inductor current;

FIG. 10 is a graph of experimentally obtained efficiency curves;

fig. 11 is a graph of the thermal performance of a prototype board under full load.

Wherein, 1 is a winding, 2 is a lower end plate, 3 is an upper end plate, 4 is a supporting column, and 5 is a magnetic core.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

There is shown in the drawings a schematic block diagram of a disclosed embodiment in accordance with the invention. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.

A schematic diagram of a four-phase buck converter with a four-phase reverse-coupled inductor is shown in fig. 1, with Vin and Vo representing the input and output voltages, respectively. v1, v2, v3 and v4 are voltages across the four-phase inductor, respectively, and i1, i2, i3 and i4 are currents flowing through the four-phase inductor, respectively. L1, L2, L3 and L4 are four-phase self-inductances, respectively, and Mij (i ═ 1, 2, 3; j ═ 2, 3, 4) is the mutual inductance between the four-phase inductors.

The voltage equation for a four-phase inductor is expressed as:

for a four-phase interleaved POL converter, the waveforms of v1, v2, v3, and v4 in the steady state are divided into D <0.25, 0.25< D <0.5, 0.5< D <0.75, and D >0.75 according to the duty cycle. Fig. 2 shows waveforms of inductor voltage and current when the input voltage is 12V, the output voltage is 1.8V, the duty ratio D is less than 0.25, and only the duty ratio D is less than 0.25 and the duty ratio D is less than 0.25.

Referring to fig. 3, the four-phase symmetric reverse coupling magnetic integrated inductor according to the present invention includes an upper end plate 3, a lower end plate 2, and four magnetic cores 5, wherein the four magnetic cores 5 are located between the upper end plate 3 and the lower end plate 2, and the four magnetic cores 5 are respectively sleeved with windings 1, the four windings 1 have the same structure, and the windings 1 on the four magnetic cores 5 are symmetrically distributed.

All be provided with support column 4 between two adjacent magnetic cores 5, the number of piles of winding 1 is one deck or multilayer on same magnetic core 5, and wherein, the number of piles of winding 1 is confirmed according to the inductance value of inductor on same magnetic core 5, and upper end plate 3 and lower end plate 2 are square structure, and four magnetic cores 5 are along circumference evenly distributed, and each support column 4 is along circumference evenly distributed.

Fig. 4 is a model of a magnetic circuit according to the invention, wherein R1 denotes the reluctance of the core arm, R2 denotes the reluctance associated with the corresponding core 5 length w2+ w3, and R3 denotes the reluctance associated with the corresponding core 5 length w2+ w3

Related magnetic resistance, Rg is the magnetic resistance of the air gap, and the self-inductance, mutual inductance and coupling coefficient among the four windings 1 can be obtained through theoretical calculation, wherein the self-inductance is as follows:

the mutual inductance is as follows:

the winding 1 of the four-phase counter-coupled inductor of the present invention was laid out with 4 layers of PCB each laid with a copper thickness of 2 ounces as shown in fig. 5a to 5d, with arrows indicating the direction of current flow.

The prototype of the invention is designed through finite element simulation, the core material adopts ferrite, the winding 1 adopts PCB copper wiring, the number of turns of each phase of winding 1 is N-2, and the picture of the magnetic core 5 is shown in figure 6.

The prototype of the invention was simulated by Q3D software, and table 1 shows the simulated self-inductance and mutual inductance values. The simulation results in table 1 verify the same inductor parameters of the present invention.

TABLE 1

TABLE 2

As shown in FIG. 7, a GaN-based prototype operating at a switching frequency of 500kHz was constructed and tested, and the self-inductance and mutual inductance were measured by LCR analyzer E4980A, as shown in Table 2. The prototype measured output voltage and high-side driver waveforms and first phase inductor current are shown in fig. 8. as can be seen from fig. 8, the inductor current ripple in the first phase buck converter is 10.4A, and the inductor current waveform has eight equivalent inductance values, close to the design result.

Fig. 9 is an experimental waveform of four-phase inductor current with a theoretical coupling coefficient of-0.142, each phase current has a ripple of about 10A, and each phase current waveform is consistent with theoretical analysis and FEA simulation results, which proves that the inductance parameters of the present invention are the same.

Fig. 10 shows the measured efficiency of the POL prototype with the proposed core 5, measured as 87.9% peak efficiency and 80.7% efficiency at full load when the output current reaches 24A. Because the experimental prototype adopts the GaN device, the measuring efficiency is higher than that of the device commonly used in the industry at present, and therefore the switching loss under high frequency is reduced.

Fig. 11 shows the thermal performance of the prototype at full load, as measured by FLIR ONE PRO, at an ambient temperature of 25 c, with a maximum temperature of 97 c observed on the board, and the hot spot occurring on the second phase synchronous rectifier, with a typical temperature of about 89.8 c for the entire circuit board, showing that the prototype of the design has excellent thermal dissipation performance.

Claims

1. A four-phase symmetrical inversely coupled magnetic integrated inductor, characterized in that it comprises an upper end plate (3), a lower end plate (2) and four magnetic cores (5), wherein the four magnetic cores (5) are located at the upper end Between the plate (3) and the lower end plate (2), windings (1) are sleeved on the four magnetic cores (5), and the windings (1) on the four magnetic cores (5) are symmetrically distributed.

2 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the windings ( 1 ) on the four magnetic cores ( 5 ) have the same structure. 3 .

3 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein a support column ( 4 ) is provided between two adjacent magnetic cores ( 5 ). 4 .

4 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the layers of the windings ( 1 ) on the same magnetic core ( 5 ) are all one layer. 5 .

5 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the layers of the windings ( 1 ) on the same magnetic core ( 5 ) are all multi-layers. 6 .

6 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the number of layers of the winding ( 1 ) on the same magnetic core ( 5 ) is determined according to the inductance value of the inductor. 7 .

7 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the upper end plate ( 3 ) and the lower end plate ( 2 ) are all square structures. 8 .

8 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein the four magnetic cores ( 5 ) are uniformly distributed along the circumferential direction. 9 .

9 . The four-phase symmetrical inversely coupled magnetic integrated inductor according to claim 1 , wherein each support column ( 4 ) is evenly distributed along the circumferential direction. 10 .