Integrated filter inductor and interleaved parallel converter

Abstract

The invention provides an integrated filter inductor and an interleaving converter. The integrated filter inductor comprises a magnetic core, a first winding, a second winding and a third winding, the magnetic core comprises an upper yoke, a lower yoke, a middle core column, a left side core column and a right side core column, the middle core column, the left side core column and the right side core column are all perpendicular to the upper yoke and the lower yoke. The first winding is wound on the middle core column, the second winding is wound on the left side core column, and the third winding is wound on the right side core column; the first winding is positively coupled with the second winding and the third winding, and the second winding is reversely coupled with the third winding; the input end of the first winding is connected with one phase of a power grid, and the output end is connected with the input ends of the left winding and the right winding; and the output end of the left winding and the output end of the right winding are electrically connected with the midpoints of two same-phase bridge arms of the interleaving parallel converter respectively, so that the number of magnetic elements in the interleaving parallel converter can be reduced, and the power density of the interleaving parallel device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an integrated filter inductor and an interleaved parallel converter. Background Art

[0002] Due to the limitation of device current and heat generation, AC-DC or DC-AC converters generally adopt the method of device parallel connection or two-way parallel connection to meet the needs of high-power transmission. However, there is the problem of device current sharing in device parallel connection, so it is rarely used in actual projects. Two-way staggered parallel connection is an effective way to increase the power output capacity of single-phase or three-phase AC-DC or DC-AC converter devices, disperse the loss distribution and reduce the total current ripple, and has been widely used in engineering. However, staggered parallel connection will lead to inconsistent potentials at the midpoints of the two bridge arms, and then form a circulating current between the bridge arms, which will cause additional losses. In order to reduce the circulating current of the bridge arm, differential mode inductors are often used in actual projects in the form of tightly coupled reverse coupled inductors in series as filter inductors between the power grid and the converter. The role of differential mode inductors is the same as that of conventional filter inductors, which are used to attenuate the high-frequency components in the grid-connected current; tightly coupled reverse coupled inductors can form a large equivalent inductance in the circulating current path, which is mainly used to suppress the circulating current formed between the bridge arms due to inconsistent switch drive, and is an indispensable and important component of staggered parallel AC-DC converters. The two inductors, the differential mode inductor and the coupled inductor, will occupy a larger board area, resulting in a decrease in the overall power density of the converter device.

[0003] Magnetic coupled inductors can be used in both staggered parallel AC-DC or DC-AC converters and staggered parallel DC-DC converters. Currently, the most research is on magnetic coupled inductors for staggered parallel DC-DC converter scenarios. An existing solution proposes a coupled inductor core combination solution with different magnetic materials, different magnetic permeabilities, and different sizes of magnetic cores. Its applicable scenario is the staggered parallel connection of two or more DC-DC converters; however, this structure only has coupled inductors and lacks differential mode inductors, which cannot meet the filtering requirements of staggered parallel AC-DC converters. For the application of coupled inductors in staggered parallel AC-DC or DC-AC converters, another solution proposes a solution of two or more coupled inductors in series. The purpose of controlling the coupling coefficient between the windings is achieved by changing the ratio of the two inductor windings on each magnetic core, which brings about the problem of an increase in the number of magnetic cores, increases the board area, and increases the processing complexity. Summary of the invention

[0004] The present invention provides an integrated filter inductor and an interleaved parallel converter, which are used to reduce the number of magnetic elements in the interleaved parallel converter device and improve the power density of the interleaved parallel device.

[0005] According to one aspect of the present invention, there is provided an integrated filter inductor, comprising: a magnetic core, a first winding, a second winding and a third winding; The magnetic core comprises: an upper yoke, a lower yoke, a middle core column, and a left core column and a right core column arranged symmetrically to the middle core column; The upper yoke and the lower yoke are symmetrically arranged; the middle core column, the left core column and the right core column are all arranged perpendicular to the upper yoke and the lower yoke; The first winding is wound on the middle core column, the second winding is wound on the left core column, and the third winding is wound on the right core column; the first winding is forward coupled with the second winding, the first winding is forward coupled with the third winding, and the second winding is reversely coupled with the third winding; The input end of the first winding is connected to one phase of the power grid, and the output end is respectively connected to the input end of the left winding and the input end of the right winding; the output end of the left winding and the output end of the right winding are respectively electrically connected to two bridge arm circuits of the same phase of the staggered parallel converter.

[0006] Optionally, the number of coil turns of the second winding wound on the left core column is the same as the number of coil turns of the third winding wound on the right core column; the direction in which the second winding is wound on the left core column is the same as the direction in which the third winding is wound on the right core column.

[0007] A first closed magnetic circuit is formed between the left half of the upper yoke, the left half of the lower yoke, the left core column and the middle core column; A second closed magnetic circuit is formed between the right half of the upper yoke, the right half of the lower yoke, the right core column and the middle core column.

[0008] A third closed magnetic circuit is formed among the upper yoke, the lower yoke, the left core column and the right core column.

[0009] Optionally, the first closed magnetic circuit and the second closed magnetic circuit are symmetrical about the middle core column.

[0010] Optionally, the left core column and the right core column are made of the same magnetic material; The upper yoke and the lower yoke are made of the same magnetic material; The material of the upper yoke and the lower yoke is different from the material of the left core column and the right core column.

[0011] Optionally, the upper yoke, the lower yoke, the left core column and the right core column are all made of magnetic materials with the same magnetic properties; The middle core column uses a magnetic material different from that of the upper yoke, the lower yoke, the left core column and the right core column.

[0012] Optionally, the cross section of the middle core column is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle; The cross-sectional shape of the left core column and the right core column is the same, and is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle.

[0013] Optionally, the first winding, the second winding and the third winding are all one of a flat copper wire winding, a Litz wire winding, a PCB winding and an enameled wire winding.

[0014] According to a second aspect of the present invention, there is also provided an interleaved parallel converter, comprising an integrated filter inductor, a grid power supply side and an interleaved parallel bridge arm circuit; The input end of the integrated filter inductor is electrically connected to the power supply side of the power grid; the output end of the integrated filter inductor is electrically connected to the bridge arm circuits that are staggered in parallel.

[0015] Optionally, a single-phase power supply on the grid power supply side is electrically connected to an input end of the integrated filter inductor, and two output ends of the integrated filter inductor are electrically connected to midpoints of two bridge arm circuits that are staggered in parallel, respectively.

[0016] The technical solution of the present invention reduces the number of magnetic elements in the staggered parallel converter device by integrating the differential mode inductor and the coupled inductor on a magnetic core, thereby improving the power density of the staggered parallel converter device; wherein, the input end of the first winding is connected to one phase of the power grid, and the output end is respectively connected to the input end of the left winding and the input end of the right winding; the output end of the left winding and the output end of the right winding are used to connect to the two bridge arm circuits of the same phase of the staggered parallel converter, and when the coupling coefficient between the second and third windings is not 1, the difference between the self-inductance of the second winding and the mutual inductance between the second and third windings and the difference between the self-inductance of the third winding and the mutual inductance between the third and second windings are connected in parallel to form a part of the equivalent differential mode inductance. Through the forward coupling of the first winding and the second winding and the forward coupling of the first winding and the third winding, the first winding interlinks part of the magnetic flux generated by the second and third windings, and this part of the magnetic flux can also generate a part of the differential mode inductance, thereby being able to obtain a larger equivalent differential mode inductance when the self-inductance of the first winding is small, so that the number of coil turns of the first winding can be reduced, thereby reducing copper loss. Through the reverse coupling of the second winding and the third winding, the equivalent inductance on the circulating current path is the sum of the self-inductance of the second winding, the self-inductance of the third winding, the mutual inductance of the second winding and the third winding, and the mutual inductance between the third winding and the second winding, thereby increasing the equivalent inductance of the circulating current, thereby suppressing the amplitude of the circulating current formed between the same-phase bridge arms in the staggered parallel converter due to inconsistent switch drive, which is beneficial to reducing losses. The input end of the integrated filter inductor can be electrically connected to one phase of the power grid, and the two output ends of the integrated filter inductor can be respectively connected to two staggered parallel bridge arm circuits. For a three-phase power supply, each phase of the power supply can be electrically connected to the input ends of three integrated filter inductors respectively, and the two output ends of each integrated filter inductor can be respectively connected to the two staggered parallel bridge arm circuits of the phase.

[0017] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of the structure of an integrated filter inductor provided in an embodiment of the present invention; Figure 2A circuit connection diagram of a two-way staggered parallel three-phase converter using three-winding coupled inductors as filter inductors in an embodiment of the present invention; Figure 3 A schematic diagram of circuit connection of two staggered parallel single-phase converters in an embodiment of the present invention; Figure 4 is an equivalent circuit diagram of a three-winding coupled inductor in an embodiment of the present invention; Figure 5 The core size of the three-winding coupled inductor in the embodiment of the present invention is defined; Figure 6 : is a finite element simulation magnetic flux distribution diagram of a three-winding coupled inductor in an embodiment of the present invention; Figure 7 The waveform diagram of the A-phase current and its ripple of the power grid simulated by the two-way staggered three-phase Vienna rectifier circuit using three-winding coupled inductors in the embodiment of the present invention; Figure 8 This is a waveform diagram of the A-phase current of two modules and the A-phase bridge arm circulating current of a two-way staggered three-phase Vienna rectifier circuit simulated using three-winding coupled inductors in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] The following uses a two-way staggered parallel three-phase Vienna rectifier as an application scenario to illustrate the characteristics and advantages of the proposed three-winding coupled inductor. Staggered parallel connection will cause the midpoint potential of the two same-phase bridge arms in the Vienna rectifier circuit to be inconsistent, which will then form a circulating current between the bridge arms and cause additional losses. In order to reduce the circulating current in the bridge arms, differential mode inductors are often used in series with tightly coupled reverse coupled inductors as filter inductors between the power grid and the converter in actual projects.

[0023] The technical solution of the embodiment of the present invention can reduce the number of magnetic components and improve the power density of the staggered parallel converter device by integrating the differential mode inductor and the coupled inductor on one magnetic core. Figure 1 This is an embodiment of the three-winding coupled inductor provided by the present invention. The integrated filter inductor includes: A magnetic core, a first winding, a second winding and a third winding.

[0024] The magnetic core comprises an upper yoke, a lower yoke, a middle core column, and a left core column and a right core column which are symmetrically arranged with respect to the middle core column.

[0025] like Figure 1 As shown, the upper yoke and the lower yoke in the magnetic core are arranged in parallel laterally or almost in parallel; the middle core column, the left core column and the right core column are also arranged in parallel vertically or almost in parallel, and the middle core column, the left core column and the right core column are all arranged perpendicularly or almost perpendicularly to the upper yoke and the lower yoke; and the left core column and the right core column are respectively arranged on both sides of the middle core column, symmetrically about the middle core column.

[0026] The upper yoke and the lower yoke are symmetrically arranged; the middle core column, the left core column and the right core column are all arranged perpendicular to the upper yoke and the lower yoke.

[0027] The first winding is wound on the middle core column, the second winding is wound on the left core column, and the third winding is wound on the right core column; when the coupling coefficient between the second and third windings is not 1, the difference between the self-inductance of the second winding and the mutual inductance between the second and third windings and the difference between the self-inductance of the third winding and the mutual inductance between the third and second windings can form a part of the equivalent differential mode inductance by connecting them in parallel. The first winding is positively coupled with the second winding, and the first winding is positively coupled with the third winding; so that the first winding interlinks part of the magnetic flux generated by the second and third windings, and this part of the magnetic flux can also generate a part of the differential mode inductance, thereby being able to obtain a larger equivalent differential mode inductance when the self-inductance of the first winding is small, so that the number of turns of the coil of the first winding can be reduced, thereby reducing the copper loss. The input end of the first winding is connected to one phase of the power grid, and the output end is respectively connected to the input end of the left winding and the input end of the right winding; the output end of the left winding and the output end of the right winding are respectively used to be electrically connected to the two bridge arm circuits of the staggered parallel converter, and the second winding is reversely coupled with the third winding to suppress the amplitude of the circulating current formed between the same-phase bridge arms in the staggered parallel converter due to inconsistent switch driving.

[0028] like Figure 1 In the invention, the input end a of the first winding is connected to a one-phase power supply of the power grid; the output end b of the first winding is respectively connected to the input end d of the second winding and the input end f of the third winding; the output end c of the second winding and the output end e of the third winding are respectively connected to two staggered parallel Vienna circuits, that is, the differential mode inductance generated on the second winding is connected in parallel with the differential mode inductance generated on the third winding, and then connected in series with the differential mode inductance generated on the first winding to form a fundamental wave equivalent inductance. This arrangement can make the value of the power grid current ripple smaller under a larger fundamental wave equivalent inductance; in addition, in the two Vienna circuits of the same phase, since the circulating current inductance generated on the second winding between the same-phase bridge arms and the circulating current inductance generated on the third winding are connected in series to generate a larger circulating current equivalent inductance, the amplitude of the circulating current formed between the same-phase bridge arms in the staggered parallel converter due to inconsistent switch drive can be suppressed, thereby reducing the circulating current amplitude, which is beneficial to reducing losses. In this embodiment, the inductance generated on the first winding includes the self-inductance generated on the first winding, the mutual inductance of the second winding to the first winding, and the mutual inductance of the third winding to the first winding; the inductance generated on the second winding includes the self-inductance generated on the second winding, the mutual inductance of the first winding to the second winding, and the mutual inductance of the third winding to the second winding; the inductance generated on the third winding includes the self-inductance generated on the third winding, the mutual inductance of the second winding to the third winding, and the mutual inductance of the first winding to the third winding.

[0029] The technical solution of the present invention reduces the number of magnetic elements in the staggered parallel converter device by integrating the differential mode inductor and the coupled inductor on a magnetic core, thereby improving the power density of the staggered parallel converter device; the input end of the first winding is connected to one phase of the power grid, and the output end is respectively connected to the input end of the left winding and the input end of the right winding; the output end of the left winding and the output end of the right winding are used to connect to the two bridge arm circuits of the same phase of the staggered parallel converter, and when the coupling coefficient between the second and third windings is not 1, the difference between the self-inductance of the second winding and the mutual inductance between the second and third windings and the difference between the self-inductance of the third winding and the mutual inductance between the third and second windings are connected in parallel to form a part of equivalent differential mode inductance. Through the forward coupling of the first winding and the second winding, and the forward coupling of the first winding and the third winding, the first winding interlinks part of the magnetic flux generated by the second and third windings, and this part of the magnetic flux can also generate a part of the differential mode inductance, thereby being able to obtain a larger equivalent differential mode inductance when the self-inductance of the first winding is small, so that the number of coil turns of the first winding can be reduced, thereby reducing copper loss. Through the reverse coupling of the second winding and the third winding, the equivalent inductance on the circulating current path is the sum of the self-inductance of the second winding, the self-inductance of the third winding, the mutual inductance between the second winding and the third winding, and the mutual inductance between the third winding and the second winding, thereby increasing the equivalent inductance of the circulating current, thereby suppressing the amplitude of the circulating current formed between the same-phase bridge arms in the staggered parallel converter due to inconsistent switch drive, which is conducive to reducing losses.

[0030] In one embodiment, the number of coil turns of the second winding wound on the left core column is the same as the number of coil turns of the third winding wound on the right core column; the direction in which the second winding is wound on the left core column is the same as the direction in which the third winding is wound on the right core column.

[0031] In one embodiment, the cross section of the middle core column is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle; The cross-sectional shape of the left core column and the right core column is the same, which is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle; The cross-sectional shape of the upper yoke and the lower yoke is the same, and is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle.

[0032] To ensure that the mutual inductance of the first winding to the second winding is the same as the mutual inductance of the first winding to the third winding, the left core column and the right core column can be set to have the same shape and the same cross-section, and the upper yoke and the lower yoke can be set to have the same shape and the same cross-section.

[0033] In one embodiment, the first winding, the second winding and the third winding are all one of a flat copper wire winding, a Litz wire winding, a PCB winding and an enameled wire winding.

[0034] In one embodiment, the left core column and the right core column are made of the same magnetic material; the upper yoke and the lower yoke are made of the same magnetic material; the middle core column uses a magnetic material different from the upper yoke, the lower yoke, the left core column and the right core column. That is, the left core column and the right core column can use materials with the same magnetic permeability; the upper yoke and the lower yoke can use materials with the same magnetic permeability; the middle core column can use materials with different magnetic permeabilities from the left core column and the right core column, or the upper yoke and the lower yoke.

[0035] Furthermore, the upper yoke, the lower yoke, the left core column and the right core column can all be made of magnetic materials with the same magnetic properties, that is, the upper yoke, the lower yoke, the left core column and the right core column have the same magnetic permeability. The upper and lower yokes and the left and right core columns can also be made of magnetic materials with different magnetic properties, that is, the upper and lower yokes are made of one magnetic material, and the left and right core columns are made of another magnetic material.

[0036] The number of coil turns of the second winding wound on the left core column is the same as the number of coil turns of the third winding wound on the right core column; the direction in which the second winding is wound on the left core column is the same as the direction in which the third winding is wound on the right core column, and since the left core column and the right core column are symmetrical about the central core column, the left core column and the right core column are both made of magnetic materials with the same magnetic properties, and the cross-sectional shapes of the left core column and the right core column are the same, therefore, the self-inductance of the second winding is the same as the self-inductance of the third winding, and the mutual inductance of the first winding to the second winding is the same as the mutual inductance of the first winding to the third winding.

[0037] The present invention also provides an interleaved parallel converter, comprising an integrated filter inductor, a grid power supply side and an interleaved parallel bridge arm circuit; the input end of the integrated filter inductor is electrically connected to the grid power supply side; the output end of the integrated filter inductor is electrically connected to the interleaved parallel bridge arm circuit.

[0038] In one embodiment, a phase power supply on the grid power supply side is electrically connected to an input end of the integrated filter inductor, and two output ends of the integrated filter inductor are electrically connected to midpoints of two bridge arm circuits that are staggered in parallel, respectively.

[0039] The circuit connection diagram of the two-way staggered parallel three-phase Vienna rectifier using three-winding coupled inductors as filter inductors is as follows: Figure 2 shown. Figure 2 In the three-phase converter, each of the three-phase voltages is connected to an integrated filter inductor, and the output end of each integrated filter inductor is electrically connected to the Vienna rectifier. Figure 2 The three integrated filter inductors are all exactly the same integrated filter inductors. Therefore, the following embodiments will only describe the integrated filter inductor and Vienna rectifier on one phase.

[0040] In one embodiment, a single-phase circuit connection diagram of two staggered parallel three-phase Vienna rectifiers using three-winding coupled inductors as filter inductors is shown in FIG. Figure 3 shown. Figure 3 In the embodiment, a phase of the power grid is electrically connected to the input terminal a of the first winding, and the output terminal b of the first winding is electrically connected to the input terminal d of the second winding and the input terminal f of the third winding respectively; the output terminal c of the second winding is connected to the midpoint of the first bridge arm of the Vienna rectifier and the first end of the switch device S1; the output terminal e of the third winding is electrically connected to the midpoint of the second bridge arm of the Vienna rectifier and the first end of the switch device S2; the second end of the switch device S1 and the second end of the switch device S2 are both connected to the midpoint of the capacitor. Among them, diodes D1, D2 and switch device S1 form the first bridge arm circuit of a certain phase; the anode of diode D1 is connected to the cathode of diode D2, and the connection point is called the midpoint of the first bridge arm circuit; diodes D3, D4 and switch device S2 form the second bridge arm circuit of the phase; the anode of diode D3 is connected to the cathode of diode D4, and the connection point is called the midpoint of the second bridge arm circuit; the cathode of diode D1 and the cathode of diode D3 are electrically connected to the positive DC bus, and the anode of diode D2 and the anode of diode D4 are electrically connected to the negative DC bus; two capacitors C1 and C2 are connected in series between the positive DC bus and the negative DC bus, and the two capacitors C1 and C2 are connected, and the connection point is called the capacitor midpoint. Switches S1 and S2 are both series connections of two fully controlled devices, the two fully controlled devices constituting S1 share a driving signal for driving, and the two fully controlled devices constituting S2 share another driving signal for driving, and there is a 180° phase difference between the driving signals of S1 and S2.

[0041] In one embodiment, for Figure 1 For the integrated filter inductor, the self-inductance of the first winding on the middle core column can be defined as L1, and the number of turns can be N1; the self-inductance of the second winding wound on the left core column can be defined as L2, and the number of turns can be N2; the self-inductance of the third winding wound on the right core column can be defined as L3, and the number of turns can be N3. There is mutual inductance flux between the first winding, the second winding, and the third winding, where the first winding and the second winding, and the first winding and the third winding are all forward coupled, and their mutual inductance can be set to M12 and M13 respectively. The second winding and the third winding are reversely coupled, and their mutual inductance can be set to M23. According to Figure 1 The direction of the current and the winding direction of the winding, the same-named ends of the first winding and the second winding are end a and end d; the same-named ends of the first winding and the third winding are end a and end f, and the same-named ends of the second winding and the third winding are end d and end e.

[0042] When L2=L3 and M 12 =M 13When , the coupling coefficient between the first winding and the second winding is equal to the coupling coefficient between the first winding and the third winding, which is defined as k1; the coupling coefficient between the second winding and the third winding is defined as k2, then:

[0043]

[0044] The equivalent circuit analysis method is often used to analyze circuits containing coupled inductors. The equivalent circuit diagram of a three-winding coupled inductor is shown below: Figure 4 As shown, Figure 4 Its fundamental equivalent inductance L eq L1-M 23 +M 12 +M 13 and (L2-M 13 +M 12 +M 23 ) / / (L3-M 12 +M 13 +M 23 ) in series, where (L2-M 13 +M 12 +M 23 ) / / (L3-M 12 +M 13 +M 23 ) represents (L2-M 13 +M 12 +M 23 ) and (L3-M 12 +M 13 +M 23 ) in parallel, since L2=L3 and M 12 =M 13 , so the expression of Leq is:

[0045] Its circulating inductance L cir =(L2-M 13 +M 12 +M 23 ) and (L3-M 12 +M 13 +M 23 ), so L cir The expression is:

[0046] The coupling coefficient between the windings can be determined according to the required equivalent fundamental inductance and circulating inductance, and then the required magnetic resistance of each magnetic circuit can be obtained, which can guide the selection of the magnetic permeability of the magnetic core material of the middle core column, the upper yoke, the lower yoke, the left core column and the right core column. This embodiment avoids increasing the length of the magnetic circuit to make the magnetic resistance of the magnetic circuit meet the requirements or increasing the cross-sectional area of ​​the magnetic circuit to make the maximum magnetic density meet the requirements, ensuring that the size of the magnetic core does not change with the change of the coupling coefficient, and only needs to change the material of the core column to be suitable for high power density occasions.

[0047] In a specific embodiment, the following can be used: Figure 5 The core size of the integrated filter inductor shown in the figure is used for a specific simulation experiment. Its winding uses flat copper wire. The cross-sections of the upper yoke, lower yoke, left core column, right core column and middle core column in the core are all square. The upper yoke, lower yoke, left core column and right core column are all made of materials with the same magnetic permeability. The core size and flat copper wire parameters are shown in Table 1 below: Table 1 Parameters of core size of integrated filter inductor

[0048] According to the parameters in the above table, a finite element simulation model of the magnetic field is built, and its magnetic density distribution can be obtained as follows: Figure 6 As shown, it can be seen that the magnetic flux density at the current peak is about 0.68T. Since the selected material is a magnetic powder core, 0.68T will not cause the core to saturate. The self-inductance and mutual inductance of each winding obtained by simulation are shown in Table 2 below: Table 2 Self-inductance and mutual inductance between windings

[0049] In Table 2, the self-inductance of the first winding is 3.6629uH; the mutual inductances of the first winding, the second winding and the third winding are 11.363uH and 11.361uH respectively; the self-inductance of the second winding is 212.89uH; the mutual inductance of the second winding and the third winding is -65.655uH; the self-inductance of the third winding is 212.89uH. It can be seen that L2=L3, M 12 ≈M 13 , which is consistent with the analysis.

[0050] According to the self-inductance and mutual inductance of each winding obtained in the above table, it can be known that the fundamental equivalent inductance L of the three-winding inductance eq =100.0024uH, circulating inductance L cir=557.09uH. A simulation model of a 40kW two-way staggered parallel three-phase Vienna rectifier circuit using the designed three-winding coupled inductor filter was built. In the simulation, the rated power of each three-phase Vienna rectifier module is 20kW, the effective value of the grid-side line voltage is 380V, and the DC-side voltage is 650V. The current and current ripple of the grid phase A, as well as the current and bridge arm circulation current on the two Vienna circuits of phase A are obtained as follows: Figure 7 , Figure 8 shown.

[0051] Depend on Figure 7 It can be seen that, ignoring the current zero-crossing distortion, the peak-to-peak value of the grid current ripple under the action of the fundamental equivalent inductance of 100.0024uH is 3.4A. Figure 8 It can be seen that the peak-to-peak value of the circulating current between the in-phase bridge arms of the two modules is 7A under the action of the circulating current inductance of 557.09uH. Due to the small amplitude of the circulating current, the currents of the two modules are almost overlapped, which meets the actual engineering requirements. Compared with the traditional differential mode inductor and coupled inductor in series, since the three-winding coupled inductor only needs one magnetic core, the board area can be significantly reduced, which helps to improve the power density of the two-way staggered parallel Vienna rectifier device.

[0052] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0053] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated filter inductor, characterized in that: comprising a magnetic core, a first winding, a second winding and a third winding; The magnetic core comprises: an upper yoke, a lower yoke, a middle core column, and a left core column and a right core column arranged symmetrically to the middle core column; The upper yoke and the lower yoke are symmetrically arranged; the middle core column, the left core column and the right core column are all arranged perpendicular to the upper yoke and the lower yoke; The first winding is wound on the middle core column, the second winding is wound on the left core column, and the third winding is wound on the right core column; the first winding is forward coupled with the second winding, the first winding is forward coupled with the third winding, and the second winding is reversely coupled with the third winding; The input end of the first winding is connected to one phase of the power grid, and the output end is respectively connected to the input end of the left winding and the input end of the right winding; the output end of the left winding and the output end of the right winding are respectively electrically connected to two bridge arm circuits of the same phase of the staggered parallel converter.

2. The integrated filter inductor according to claim 1, characterized in that: The number of coil turns of the second winding wound on the left core column is the same as the number of coil turns of the third winding wound on the right core column; the direction in which the second winding is wound on the left core column is the same as the direction in which the third winding is wound on the right core column.

3. The integrated filter inductor according to claim 1, characterized in that: A first closed magnetic circuit is formed between the left half of the upper yoke, the left half of the lower yoke, the left core column and the middle core column; A second closed magnetic circuit is formed between the right half of the upper yoke, the right half of the lower yoke, the right core column and the middle core column; A third closed magnetic circuit is formed among the upper yoke, the lower yoke, the left core column and the right core column.

4. The integrated filter inductor according to claim 3, characterized in that: The first closed magnetic circuit and the second closed magnetic circuit are symmetrical about the middle core column.

5. The integrated filter inductor according to claim 1, characterized in that: The left core column and the right core column are made of the same magnetic material; The upper yoke and the lower yoke are made of the same magnetic material; The material of the upper yoke and the lower yoke is different from the material of the left core column and the right core column.

6. The integrated filter inductor according to claim 1, characterized in that: The upper yoke, the lower yoke, the left core column and the right core column are all made of magnetic materials with the same magnetic properties; The middle core column uses a magnetic material different from that of the upper yoke, the lower yoke, the left core column and the right core column.

7. The integrated filter inductor according to claim 1, characterized in that: The cross section of the middle core column is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle; The cross-sectional shape of the left core column and the right core column is the same, which is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle; The cross-sectional shape of the upper yoke and the lower yoke is the same, and is one of a circle, an ellipse, a triangle, a square, a rectangle, a rounded rectangle and a rounded triangle.

8. The integrated filter inductor according to claim 1, characterized in that: The first winding, the second winding and the third winding are all selected from the group consisting of a flat copper wire winding, a Litz wire winding, a PCB winding and an enameled wire winding.

9. An interleaved parallel converter, characterized in that: The integrated filter inductor comprises the integrated filter inductor according to any one of claims 1 to 8, and further comprises a power grid power supply side and a bridge arm circuit connected in staggered parallel; The input end of the integrated filter inductor is electrically connected to the power supply side of the power grid; the output end of the integrated filter inductor is electrically connected to the bridge arm circuits that are staggered in parallel.

10. The interleaved parallel converter according to claim 9, characterized in that: A single-phase power supply on the grid power supply side is electrically connected to the input end of the integrated filter inductor, and two output ends of the integrated filter inductor are electrically connected to the midpoints of the two bridge arm circuits that are staggered in parallel, respectively.

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