阅读说明：本技术 组合滤波器及其制造方法 (Combined filter and manufacturing method thereof ) 是由 刘艺涛 江师齐 于 2019-08-26 设计创作，主要内容包括：本发明公开了一种组合滤波器及其制造方法,组合滤波器包括单相谐波滤波电路和电磁干扰滤波电路,单相谐波滤波电路的网侧电感与电磁干扰滤波电路的共模电感通过磁集成形成集成电感。本发明提出的一种组合滤波器,通过将单独位于火线上的逆变器侧电感L<Sub>1</Sub>和网侧电感L<Sub>2</Sub>等效拆分为分别位于火线和零线上的逆变器侧电感<Image he="71" wi="60" file="DDA0002179939050000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>和网侧电感<Image he="72" wi="90" file="DDA0002179939050000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>以使单相谐波滤波器的滤波电路为对称的滤波电路,然后将拆分后的单相谐波滤波电路的逆变器侧电感<Image he="77" wi="92" file="DDA0002179939050000013.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>网侧电感值<Image he="72" wi="60" file="DDA0002179939050000014.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>与电磁干扰滤波电路的共模电感值L<Sub>CM</Sub>通过磁集成方法形成集成电感；通过本发明的技术方案,将避免共模(CM)噪声向差模(DM)噪声的转化,降低差模噪声的实测幅值,也减小了整个输出滤波器的体积和重量。(The invention discloses a combined filter and a manufacturing method thereof, wherein the combined filter comprises a single-phase harmonic filter circuit and an electromagnetic interference filter circuit, and a network side inductor of the single-phase harmonic filter circuit and a common mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration. The combined filter provided by the invention is formed by arranging an inverter side inductor L on a live wire separately 1 And network side inductance L 2 Equivalent split inverter side inductor on live wire and zero line respectively And network side inductor The filter circuit of the single-phase harmonic filter is used as a symmetrical filter circuit, and then the inverter side inductor of the split single-phase harmonic filter circuit Inductance value on net side Common-mode inductance value L of electromagnetic interference filter circuit CM Forming an integrated inductor by a magnetic integration method; by the technical scheme of the invention, the conversion of Common Mode (CM) noise to Differential Mode (DM) noise is avoided, the actually measured amplitude of the DM noise is reduced, and the volume and the weight of the whole output filter are also reduced.)

1. A combined filter is characterized by comprising a single-phase harmonic filter circuit and an electromagnetic interference filter circuit, wherein a network side inductor of the single-phase harmonic filter circuit and a common-mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration.

2. The combination filter of claim 1, wherein the single-phase harmonic filter circuit includes an inverter-side harmonic filter inductance, a grid-side harmonic filter inductance, and a harmonic filter capacitance, the inverter-side and grid-side inductances of the harmonic filter circuit and the common-mode inductance of the electromagnetic interference filter circuit forming an integrated inductance by magnetic integration.

3. The combination filter of claim 1, wherein the integrated inductor comprises a magnetic core and a plurality of windings, the magnetic core comprises a plurality of side legs and a center leg, a first winding is wound around the plurality of side legs for forming a common mode inductor, a second winding is wound around upper and lower portions of the center leg for forming an inverter-side and a grid-side harmonic filter inductor, and the center leg has an air gap.

4. A combined filter according to claim 3, wherein the core is an EE-type core, the center leg is divided into an upper center leg and a lower center leg by an air gap, the first winding is wound around one side leg and the other side leg in sequence, and the two branches of the first winding are wound around the upper center leg and the lower center leg, respectively.

5. The combination filter of claim 4, wherein the two branches of the second winding are wound around the upper and lower center legs, respectively, and the two branches of the second winding are located at the top of the two branches of the first winding.

6. A method of manufacturing a combined filter according to any of claims 1-5, characterised in that the method comprises:

step S10: carrying out symmetrical splitting on the harmonic filter so as to enable the filter circuit of the harmonic filter to be a symmetrical filter circuit;

step S20: establishing common and differential mode models of the electromagnetic interference filter, and determining the inductance and capacitance values of the electromagnetic interference filter through the common and differential mode models;

step S30: the inverter side and network side inductances of the harmonic filter and the common mode inductance of the electromagnetic interference filter are integrated on the same magnetic core unit through the winding and the magnetic core by magnetic integration.

7. The method of manufacturing a combination filter according to claim 6, wherein the step S10 includes:

inverter side inductor L to be located solely on live line₁And network side inductance L₂Equivalent split inverter side inductor on live wire and zero line respectively

determining inverter side inductance

8. The method of manufacturing a combination filter according to claim 6 or 7, wherein the step S20 includes:

step S201: establishing common and differential mode models of the electromagnetic interference filter, and obtaining insertion gain and insertion loss of an equivalent common mode filter circuit and an equivalent differential mode filter circuit according to the common and differential mode models so as to determine the high-frequency attenuation rate of the common mode filter;

step S202: determining a cut-off frequency required by the common mode filter according to the high-frequency attenuation rate of the common mode filter, and further determining the value of the common mode inductance according to the relation between the cut-off frequency and the resonance frequency;

step S203: and determining the differential mode insertion loss according to the insertion gain and the insertion loss of the differential mode filter circuit, determining the high-frequency attenuation rate according to the differential mode insertion loss, and determining the value of the differential mode filter inductance according to the high-frequency attenuation rate.

9. The method of manufacturing a combination filter according to claim 6, wherein the step S30 includes:

step S301: an EE type magnetic core is adopted, and a plurality of windings are wound on the EE type magnetic core to be used as harmonic wave filter inductance, so that the harmonic wave filter inductance is determined;

wherein determining the harmonic filter inductance comprises:

step S3011: determining common mode inductance;

the EE type magnetic core comprises two side columns and a center column, wherein the upper center column winding and the lower center column winding are used as harmonic wave filter inductors, and the two side column windings are N₃A common mode filter inductor is used, and the leakage inductance of the common mode filter inductor is used as a differential mode electromagnetic interference filter inductor; the common mode inductance is expressed by the following formula (1):

wherein N is₃For windings wound on two legs, R_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMRepresenting the mutual inductance between any two windings on the common-mode excitation lower side column; k_M，CMCommon mode mutual inductance coefficient;

step S3012: determining the relation between the harmonic wave filtering inductance and the center pillar winding;

the middle column winding is used as a harmonic filter inductor and comprises an upper middle column and a lower middle column winding, the upper middle column and the lower middle column are respectively used as harmonic filter inductors on an L line and an N line, the upper winding inverter side inductors of the upper middle column and the lower middle column form a grid side inductor, and the lower windings of the upper middle column and the lower middle column form a grid side inductor;

the relationship between the harmonic filter inductance and the center pillar winding is expressed by the following formula (2):

N₁a winding wound around the upper and lower center pillars, N₂Is a winding wound around the upper and lower center pillars, and N₂The winding is positioned at the N₁Below the windings.

10. The method for manufacturing a combined filter according to claim 9, wherein the step S30 further includes, after the step S3012:

step S302: determining the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, which are respectively expressed by the following formula (3) and the following formula (4):

R_S,DM＝R₂+R₁//R₁＝0.5R₁+R₂(4)

wherein R is_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMThe mutual inductance between any two windings on the lower limb of the common-mode excitation is represented, wherein the total flux generated by the common-mode coil on any limb is represented₁Representing the coupled magnetic flux, R, flowing through the other leg₁Representing the equivalent reluctance, R, under common mode excitation₂Representing the equivalent magnetoresistance under differential mode excitation;

step S303, determining the relationship between the equivalent magnetic resistance of the side column, the magnetic yoke, the center column and the center column air gap; definition of R_c1、R_c2、R_c3And R_gThe equivalent magnetic resistances of the air gaps of the side column, the yoke, the center column and the center column are respectively expressed by the following formula (5):

wherein R is_c1、R_c2、R_c3And R_gEquivalent magnetic resistances of the air gaps of the side column, the magnetic yoke, the center column and the center column respectively, wherein_s、l_yAnd l_cRespectively showing the magnetic path lengths of the side column magnetic path, the magnetic yoke, the upper center column and the lower center column; a. the_s、A_yAnd A_cRespectively showing the cross-sectional areas of the side column, the magnetic yoke and the center column of the magnetic core; mu.s₀And mu_rRespectively showing the vacuum permeability and the relative permeability of the magnetic core used;

step S304: determining a common mode inductance coupling coefficient; according to R_c1、R_c2、R_c3And R_gDetermines the common mode inductive coupling coefficient, as represented by equation (6) below:

by determining R_c1、R_c2、R_c3And R_gRelation between equivalent magnetic resistance and air gap of center pillar and common mode inductance coupling coefficient and R_c1、R_c2、R_c3And R_gThe relation of the equivalent magnetic resistance can determine the relation of the common mode inductive coupling coefficient and the air gap of the center pillar.

Step S305: judging the number of turns of the center pole winding and the total magnetic flux phi generated by differential mode excitation_DMThe size of (d);

if the number of turns of the center pillar winding is less than or equal to the total magnetic flux generated by the differential mode excitation, executing the step S306; if the number of turns of the center pole winding is greater than the total magnetic flux generated by the differential mode excitation, returning to step S302;

wherein phi_DMThe following equation (7) represents:

wherein, B_maxIs the saturation flux density of the magnetic core; a. the_eIs the effective cross-sectional area of the core; i is₂The common mode coupling coefficient is equal to or more than 0.9, N represents the total number of differential mode coils, and I represents the differential mode current value;

step S306: and outputting the number of turns of the column winding.

Technical Field

The invention relates to the field of filters, in particular to a combined filter and a manufacturing method thereof.

Background

Disclosure of Invention

The invention provides a combined filter and a manufacturing method thereof, and mainly aims to provide a combined filter with symmetrical structure and electromagnetic integration of a harmonic filter and an electromagnetic interference filter.

In order to achieve the above object, the present invention further provides a combined filter, which includes a single-phase harmonic filter circuit and an electromagnetic interference filter circuit, wherein a network side inductor of the single-phase harmonic filter circuit and a common mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration.

Optionally, the single-phase harmonic filter circuit includes an inverter-side filter inductor, a grid-side filter inductor, and a filter capacitor connected between the inverter and the grid, and the inverter-side and grid-side harmonic filter inductors and the common-mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration.

Optionally, the integrated inductor includes a magnetic core and a plurality of windings, the magnetic core includes a plurality of side columns and a center pillar, the first winding is wound around the side columns for forming a common mode inductor, the second winding is wound around the center pillar for forming an inverter side and a grid side harmonic filter inductor, and the center pillar has an air gap.

Optionally, the magnetic core is an EE-type magnetic core, the center pillar is divided into an upper center pillar and a lower center pillar by an air gap, the first winding is sequentially wound behind one side pillar and the other side pillar, and the two branches of the first winding are respectively wound around the upper center pillar and the lower center pillar.

Optionally, the two branches of the second winding are wound around the upper center pillar and the lower center pillar, respectively, and the two branches of the second winding are located at the top of the two branches of the first winding.

In order to achieve the above object, the present invention also discloses a method for manufacturing the above combined filter, the method comprising:

step S10: carrying out symmetrical splitting on the harmonic filter so as to enable the filter circuit of the harmonic filter to be a symmetrical filter circuit;

step S20: establishing common and differential mode models of the electromagnetic interference filter, and determining the inductance and capacitance values of the electromagnetic interference filter through the common and differential mode models;

step S30: the inverter side and net side inductances of the harmonic filter and the common mode inductance of the electromagnetic interference filter are integrated on the same magnetic core unit through the winding and the magnetic core by magnetic integration.

Optionally, the step S10 includes:

inverter side inductor L to be located solely on live line₁And network side inductance L₂Equivalent split inverter side inductor on live wire and zero line respectivelyAnd network side inductor

A filter circuit for making the filter circuit of the single-phase harmonic filter symmetrical;

determining inverter side inductance

And network side inductor

Value of (D) and capacitance C_fThe numerical value of (c).

Optionally, the step S20 includes:

step S201: establishing common and differential mode models of the electromagnetic interference filter, and obtaining insertion gain and insertion loss of an equivalent common mode filter circuit and an equivalent differential mode filter circuit according to the common and differential mode models so as to determine the high-frequency attenuation rate of the common mode filter;

step S202: determining a cut-off frequency required by the common mode filter according to the high-frequency attenuation rate of the common mode filter, and further determining the value of the common mode inductance according to the relation between the cut-off frequency and the resonance frequency;

step S203: and determining the differential mode insertion loss according to the insertion gain and the insertion loss of the differential mode filter circuit, determining the high-frequency attenuation rate according to the differential mode insertion loss, and determining the value of the differential mode filter inductance according to the high-frequency attenuation rate.

Optionally, the step S30 includes:

step S301: an EE type magnetic core is adopted, and a plurality of windings are wound on the EE type magnetic core to be used as harmonic wave filter inductance, so that the harmonic wave filter inductance is determined;

wherein determining the harmonic filter inductance comprises:

step S3011: determining common mode inductance;

the EE type magnetic core comprises two side columns and a center column, wherein the upper center column winding and the lower center column winding are used as harmonic wave filter inductors, and the two side column windings are N₃A common mode filter inductor is used, and the leakage inductance of the common mode filter inductor is used as a differential mode electromagnetic interference filter inductor; the common mode inductance is expressed by the following formula (1):

wherein N is₃For windings wound on two legs, R_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMRepresenting the mutual inductance between any two windings on the common-mode excitation lower side column; k_M，CMCommon mode mutual inductance coefficient;

step S3012: determining the relation between the harmonic wave filtering inductance and the center pillar winding;

the middle column winding is used as a harmonic filter inductor and comprises an upper middle column and a lower middle column winding, the upper middle column and the lower middle column are respectively used as harmonic filter inductors on an L line and an N line, the upper winding inverter side inductors of the upper middle column and the lower middle column form a grid side inductor, and the lower windings of the upper middle column and the lower middle column form a grid side inductor;

the relationship between the harmonic filter inductance and the center pillar winding is expressed by the following formula (2):

N₁a winding wound around the upper and lower center pillars, N₂Is a winding wound around the upper and lower center pillars, and N₂The winding is positioned at the N₁Below the windings.

Optionally, the step S30, after the step S3012, further includes:

step S302: determining the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, which are respectively expressed by the following formula (3) and the following formula (4):

R_s，DM＝R₂+R₁//R₁＝0.5R₁+R₂(4)

wherein R is_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMThe mutual inductance between any two windings on the lower limb of the common mode excitation is represented, wherein phi represents the total flux generated by the common mode coil on any limb, and phi represents the total flux generated by the common mode coil on any limb₁Representing the coupled magnetic flux, R, flowing through the other leg₁Representing the equivalent reluctance, R, under common mode excitation₂Representing the equivalent magnetoresistance under differential mode excitation;

step S303: determining the relation between the equivalent magnetic resistance of the side column, the magnetic yoke, the center column and the center column air gap; definition of R_c1、R_c2、R_c3And R_gThe equivalent magnetic resistances of the air gaps of the side column, the yoke, the center column and the center column are respectively expressed by the following formula (5):

wherein R is_c1、R_c2、R_c3And R_gEquivalent magnetic resistances of the air gaps of the side column, the magnetic yoke, the center column and the center column respectively, wherein_s、l_yAnd l_cRespectively showing the magnetic path lengths of the side column magnetic path, the magnetic yoke, the upper center column and the lower center column; a. the_s、A_yAnd A_cRespectively showing the cross-sectional areas of the side column, the magnetic yoke and the center column of the magnetic core; mu.s₀And mu_rRespectively showing the vacuum permeability and the relative permeability of the magnetic core used;

step S304: determining a common mode inductance coupling coefficient; according to R_c1、R_c2、R_c3And R_gDetermines the common mode inductive coupling coefficient, as represented by equation (6) below:

by determining R_c1、R_c2、R_c3And R_gRelation between equivalent magnetic resistance and air gap of center pillar and common mode inductance coupling coefficient and R_c1、R_c2、R_c3And R_gThe relation of the equivalent magnetic resistance can determine the relation of the common mode inductive coupling coefficient and the air gap of the center pillar.

Step S305: judging the number of turns of the center pole winding and the total magnetic flux phi generated by differential mode excitation_DMThe size of (d);

if the number of turns of the center pillar winding is less than or equal to the total magnetic flux generated by the differential mode excitation, executing the step S306; if the number of turns of the center pole winding is larger than the total magnetic flux generated by the differential mode excitation, returning to the step S302;

wherein phi_DMThe following equation (7) represents:

wherein, B_maxIs the saturation flux density of the magnetic core; a. the_eIs the effective cross-sectional area of the core; i is₂The common mode coupling coefficient is equal to or more than 0.9, N represents the total number of differential mode coils, and I represents the differential mode current value;

step S306: and outputting the number of turns of the column winding.

The combined filter provided by the invention has the advantages that the inverter side inductor L1 and the network side inductor L2 which are separately positioned on the live wire are equivalently split into the inverter side inductors respectively positioned on the live wire and the zero wire

And network side inductor

The filter circuit of the single-phase harmonic filter is used as a symmetrical filter circuit, and then the inverter side inductor of the split single-phase harmonic filter circuit

Inductance value on net sideCommon-mode inductance value L of electromagnetic interference filter circuit_CMForming an integrated inductor by a magnetic integration method; by the technical scheme of the invention, the conversion of Common Mode (CM) noise to Differential Mode (DM) noise is avoided, the actually measured amplitude of the DM noise is reduced, and the volume and the weight of the whole output filter are also reduced.

Drawings

Fig. 1 is a circuit diagram of a combined filter according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for manufacturing a combined filter according to an embodiment of the invention;

FIG. 3 is a schematic flow chart of step S30 in FIG. 2;

FIG. 4 is a system diagram of a method for magnetic integration of a combined filter according to an embodiment of the present invention;

FIG. 5 is a diagram illustrating a magnetic integration model of a method for magnetic integration of a combined filter according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a magnetic circuit under excitation of a common mode noise signal according to a magnetic integration method of a combined filter according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a magnetic circuit excited by a differential mode noise signal according to a magnetic integration method for a combined filter according to an embodiment of the present invention;

FIG. 8 is a simplified magnetic circuit diagram for common-mode excitation of a magnetic integration method for a combined filter according to an embodiment of the present invention;

FIG. 9 is a simplified magnetic circuit diagram under differential mode excitation for a method of magnetic integration of a combined filter according to an embodiment of the present invention;

fig. 10 is a common-mode equivalent magnetic circuit of a magnetic integration method of a combined filter according to an embodiment of the present invention;

fig. 11 is a differential mode equivalent magnetic circuit of a magnetic integration method of a combined filter according to an embodiment of the present invention;

fig. 12 is a differential mode insertion loss curve of a magnetic integration method of a combined filter according to an embodiment of the present invention;

fig. 13 is a common-mode insertion loss curve of a magnetic integration method for a combined filter according to an embodiment of the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, in order to achieve the above object, the present invention further provides a combined filter, including a single-phase harmonic filter circuit and an electromagnetic interference filter circuit, wherein inverter-side and grid-side inductors of the single-phase harmonic filter circuit and a common-mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration; optionally, the single-phase harmonic filter circuit includes inverter-side and grid-side harmonic filter inductors and a harmonic filter capacitor connected between the inverter and the grid, and the inverter-side and grid-side inductors of the single-phase harmonic filter circuit and the common-mode inductor of the electromagnetic interference filter circuit form an integrated inductor through magnetic integration; optionally, the integrated inductor includes a magnetic core and a plurality of windings, the magnetic core includes a plurality of side legs and a center leg, the first winding is wound around the side legs for forming a common mode inductor, the second winding is wound around the center leg for forming inverter side and grid side inductors, and the center leg has an air gap; optionally, the magnetic core is an EE-type magnetic core, the center pillar is divided into an upper center pillar and a lower center pillar by an air gap, the first winding is sequentially wound around one side pillar and the other side pillar, and two branches of the first winding are respectively wound around the upper center pillar and the lower center pillar; optionally, the two branches of the second winding are wound around the upper center pillar and the lower center pillar, respectively, and the two branches of the second winding are located at the top of the two branches of the first winding.

Specifically, an input end of the combined filter is electrically connected with the inductor in sequence

Capacitor C_fCapacitor C_YInductor

Inductor L_CMCapacitor C_XIn the formula

Inductor L₁And L₂The value of the inductor before splitting, and the other input end of the circuit is electrically connected with the inductor in sequence

Capacitor C_fCapacitor C_Y1InductorInductor L_CM1Capacitor C_X，

Optionally, an input terminal of the circuit passes through the inductor

Electric connection capacitor C_fOne pole of the inductorOne terminal of (1), a capacitor C_YOne terminal of, the inductanceThe other end of (1) passes through an inductor L_CMConnecting capacitor C_XA pole and an output terminal of the capacitor C_YThe other end of the capacitor C is connected with a capacitor C_y1One pole of (a);

the other input end of the combined filter passes through an inductor

Electric connection capacitor C_fAnother electrode of (1), a capacitor C_Y1Another pole of (1), inductance

One terminal of, the inductance

The other end of (1) passes through an inductor L_CM1Connecting capacitor C_XThe other pole of the first transistor and the other output terminal.

Referring to fig. 2, the present invention provides a method for manufacturing a combined filter, the method comprising:

step S10: carrying out symmetrical splitting on the harmonic filter so as to enable the filter circuit of the harmonic filter to be a symmetrical filter circuit;

step S20: establishing common and differential mode models of the electromagnetic interference filter, and determining the inductance and capacitance values of the electromagnetic interference filter through the common and differential mode models;

step S30: the inverter side and network side inductances of the harmonic filter and the common mode inductance of the electromagnetic interference filter are integrated on the same magnetic core unit through the winding and the magnetic core by magnetic integration.

Referring to fig. 3, optionally, the step S30 includes:

step S301: an EE type magnetic core is adopted, and a plurality of windings are wound on the EE type magnetic core to be used as harmonic wave filter inductance, so that the harmonic wave filter inductance is determined;

wherein determining the harmonic filter inductance comprises:

step S3011: determining common mode inductance;

the EE type magnetic core comprises two side columns and a center column, wherein the upper center column winding and the lower center column winding are used as harmonic wave filter inductors, and the two side column windings are N₃A common mode filter inductor is used, and the leakage inductance of the common mode filter inductor is used as a differential mode electromagnetic interference filter inductor; the common mode inductance is expressed by the following formula (1):

wherein N is₃For windings wound on two legs, R_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMRepresenting the mutual inductance between any two windings on the common-mode excitation lower side column; k_M，CMCommon mode mutual inductance coefficient;

step S3012: determining the relation between the harmonic wave filtering inductance and the center pillar winding;

the middle column winding is used as a harmonic filter inductor and comprises an upper middle column and a lower middle column winding, the upper middle column and the lower middle column are respectively used as harmonic filter inductors on an L line and an N line, the upper winding inverter side inductors of the upper middle column and the lower middle column form a grid side inductor, and the lower windings of the upper middle column and the lower middle column form a grid side inductor;

the relationship between the harmonic filter inductance and the center pillar winding is expressed by the following formula (2):

N₁a winding wound around the upper and lower center pillars, N₂Is a winding wound around the upper and lower center pillars, and N₂The winding is positioned at the N₁Below the winding;

step S302: determining the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, which are respectively expressed by the following formula (3) and the following formula (4):

R_s，DM＝R₂+R₁//R₁＝0.5R₁+R₂(4)

wherein R is_S，CMAnd R_S，DMRespectively representing the self-inductance magnetic resistance of the side column winding under common-mode excitation and the self-inductance magnetic resistance of the middle column winding under differential-mode excitation, M_CMThe mutual inductance between any two windings on the lower limb of the common mode excitation is represented, wherein phi represents the total flux generated by the common mode coil on any limb, and phi represents the total flux generated by the common mode coil on any limb₁Representing the coupled magnetic flux, R, flowing through the other leg₁Representing the equivalent reluctance, R, under common mode excitation₂Representing the equivalent magnetoresistance under differential mode excitation;

step S303: determining the relation between the equivalent magnetic resistance of the side column, the magnetic yoke, the center column and the center column air gap; definition of R_c1、R_c2、R_c3And R_gThe equivalent magnetic resistances of the air gaps of the side column, the yoke, the center column and the center column are respectively expressed by the following formula (5):

wherein R is_c1、R_c2、R_c3And R_gEquivalent magnetic resistances of the air gaps of the side column, the magnetic yoke, the center column and the center column respectively, wherein_s、l_yAnd l_cRespectively showing the magnetic path lengths of the side column magnetic path, the magnetic yoke, the upper center column and the lower center column; a. the_s、A_yAnd A_cRespectively showing the cross-sectional areas of the side column, the magnetic yoke and the center column of the magnetic core; mu.s₀And mu_rRespectively showing the vacuum permeability and the relative permeability of the core used；

Step S304: determining a common mode inductance coupling coefficient; according to R_c1、R_c2、R_c3And R_gDetermines the common mode inductive coupling coefficient, as represented by equation (6) below:

by determining R_c1、R_c2、R_c3And R_gRelation between equivalent magnetic resistance and air gap of center pillar and common mode inductance coupling coefficient and R_c1、R_c2、R_c3And R_gThe relation of the equivalent magnetic resistance can determine the relation of the common mode inductive coupling coefficient and the air gap of the center pillar.

Step S305: judging the number of turns of the center pole winding and the total magnetic flux phi generated by differential mode excitation_DMThe size of (d);

if the number of turns of the center pillar winding is less than or equal to the total magnetic flux generated by the differential mode excitation, executing the step S306; if the number of turns of the center pole winding is larger than the total magnetic flux generated by the differential mode excitation, returning to the step S302;

wherein phi_DMThe following equation (7) represents:

wherein, B_maxIs the saturation flux density of the magnetic core; a. the_eIs the effective cross-sectional area of the core; i is₂The common mode coupling coefficient is equal to or more than 0.9, N represents the total number of differential mode coils, and I represents the differential mode current value;

step S306: and outputting the number of turns of the column winding.

It should additionally be noted that: optionally, the step S10 includes:

step S101: inverter side inductor L to be located on live wire of single-phase harmonic filter₁And network side inductance L₂Inverter side inductor equivalently split into live wire and zero wire of single-phase harmonic filter

And network side inductor

A filter circuit for making the filter circuit of the harmonic filter symmetrical;

step S102: determining the capacitance C_fThe numerical value of (c) is represented by the following formula (8):

C_f+C_X≤C_f，max(8)

wherein, C_fIs a harmonic filter capacitor, C_XRepresents a differential mode filter capacitance;

step S103: determining inverter side inductance

Wherein the inverter side inductor

The following formula (9) represents:

wherein V_inInputting voltage for a direct current side; t is_swIs the carrier period; i is₁The effective value of the fundamental wave current at the inverter side under rated power;

is the inverter side current ripple factor, and

the value range is 20% -30%:

step S104: determining the inductance value of the filter at the net side;

the grid-side filter inductance value is determined through a limit standard of a power grid on harmonic waves, an open-loop transfer function of an inversion system of a harmonic filter and a Bessel function, wherein the limit standard of the power grid on the harmonic waves is represented by a formula (10), the open-loop transfer function of the inversion system of the harmonic filter is represented by a formula (11), and the Bessel function expression is represented by a formula (12):

wherein, J₁(π α) and J₃(π α) are each represented by (w)_sw+w₀) And (w)_sw+3w₀) Bessel function of sideband harmonics at frequency, w_swAnd w₀Angular frequencies that are the switching frequency and the fundamental frequency, respectively;

open loop transfer function for LCL inverter system, wherein I₂Measuring the current, V, for the LCL filter network_inIs the inverter side voltage value of the LCL filter; n represents the sideband width, which is measured at the fundamental frequency.

Optionally, a harmonic filter capacitor C_fMaximum value of (C)_f，maxThe following equation (13) represents:

wherein λ is_cRepresenting the ratio of the reactive power introduced by the harmonic filter inductor to the rated active power output by the inverter; p_nAnd V_gRated active power and voltage are respectively output for the inverter; f. of₀Is the fundamental frequency.

Optionally, the step S20 includes:

step S201: establishing common and differential mode models of the electromagnetic interference filter, and obtaining insertion gain and insertion loss of an equivalent common mode filter circuit and an equivalent differential mode filter circuit according to the common and differential mode models so as to determine the high-frequency attenuation rate of the common mode filter;

step S202: determining a cut-off frequency required by the common mode filter according to the high-frequency attenuation rate, and further determining the value of the common mode inductance according to the relation between the cut-off frequency and the resonance frequency;

step S203: and determining the differential mode insertion loss by using the insertion gain and the insertion loss of the differential mode filter circuit, determining the high-frequency attenuation rate according to the differential mode insertion loss, and determining the value of the differential mode filter inductance through the high-frequency attenuation rate.

Optionally, the relationship between the cut-off frequency and the resonant frequency in step S202 is that the cut-off frequency is equal to the resonant frequency.

The magnetic integration method of the combined filter is described in detail below:

referring to fig. 4, the harmonic filter capacitance C is determined by the following equation (13)_fA value of (b), wherein_cRepresenting the ratio of the reactive power introduced by the harmonic filter inductor to the rated active power output by the inverter; p_nAnd V_gRated active power and voltage are respectively output for the inverter; f. of₀Is the fundamental frequency. It should be noted that: harmonic filter capacitor C_fShould satisfy C_f+C_X≤C_f，maxAnd is in C_XWhile keeping a certain value margin C_fThe larger value should be selected as much as possible so as to reduce the required inductance design value.

The inverter-side inductance can be designed according to the following equation (9), where V_inInputting voltage for a direct current side; t is_swIs the carrier period; i is₁The effective value of the fundamental wave current at the inverter side under rated power;

for the current ripple coefficient of the inverter side, in practical engineering

Generally 20-30 percent.

The determination process of the grid-side filter inductance is described below, and a Bessel function is introduced for auxiliary design according to the limit standard of the power grid on harmonic waves. At C_fAndin the case where it has been determined that,

the design of (a) is required to satisfy the following equation (10) (i.e., the switching frequency and the three times of the switching frequency are both made to satisfy the requirements and the amplitudes of the harmonics thereof in the sidebands). Wherein J₁(π α) and J₃(π α) are each represented by (w)_sw+w₀) And (w)_sw+3w₀) Bessel function of sideband harmonics at frequency, w_swAnd w₀Angular frequencies that are the switching frequency and the fundamental frequency, respectively;

is an open loop transfer function of an inversion system of a harmonic filter (LCL filter), as shown in the following formula (11), wherein I₂Measuring the current, V, for the LCL filter network_inIs the inverter side voltage value of the LCL filter; the Bessel function expression is expressed by the following equation (12), where n represents the sideband width (measured by the fundamental frequency).

Since the electromagnetic interference filter (hereinafter, abbreviated as EMI filter) is designed based on the LCL filter, it is not necessary to consider the influence of the LCL filter when modeling the EMI filter model. The EMI filter is modeled in the equivalent common and differential modes as shown in FIG. 7, where V_CM1(V_DM1) Representing the common-mode (differential-mode) voltage, V, transmitted by a common-mode (differential-mode) noise source to the LISN before the filter is switched in_CM2(V_DM2) Representing the common mode (differential mode) voltage transmitted by a common mode (differential mode) noise source to the LISN after the filter is switched in. The insertion gain of the equivalent common-mode and differential-mode filter circuit can be obtained according to the model, and the formula (14) shows. Further, the insertion loss of the common-mode and differential-mode equivalent filters can be obtained, as shown in fig. 13, where fig. 13 shows: the high frequency attenuation rate of the common mode filter is 40dB/dec, from which the cut-off frequency f required for the common mode filter can be determined according to equation (15)_c-req，CM. Wherein f is_TFor common mode noise exceeding frequency, V_reqThe amount of attenuation (dB) required to meet the requirements at the corresponding over-standard frequencies. And for a common mode filter circuit (LC circuit), its cutoff frequency is approximately equal to its resonant frequency, as shown in equation (16). Therefore, the value interval of the common-mode capacitance is determined according to the leakage current standard, and then the required common-mode inductance is determined by combining the formulas (15) and (16). The differential mode insertion loss is shown in fig. 12, and fig. 12 shows: the high-frequency attenuation rate of the differential mode insertion loss is 60dB/dec, so the numerical value of the cut-off frequency of the differential mode filter is relatively large, and the differential mode filter capacitor is generally in a mu F level (0.1 mu F-1 mu F), and the LCL harmonic filter is improved by the invention, so the electromagnetic compatibility is improved, the required differential mode filter inductance is small, and the leakage inductance of the common mode inductor can be used for replacing; preferably, 0.1% of the common mode inductance is used as a preset differential mode inductance, and the differential mode capacitance parameter is adjusted to meet the differential mode attenuation requirement.

On the basis of determining the values of filter inductance and capacitance of each part of the LCL-EMI filter, all filter inductances are integrated into a magnetic core unit by designing a magnetic integration scheme, the flow chart of the magnetic integration LCL-EMI filter is shown in figure 4, the magnetic integration scheme is shown in figure 5, an EE type magnetic core is utilized, wherein a center pillar winding is used as a harmonic filter inductance (an upper center pillar winding and a lower center pillar winding are respectively used as harmonic filter inductances on an L line and an N line, and a center pillar winding N is used as a harmonic filter inductance on the L line and the N line₁That is, the second winding includes: the first coil and the second coil are wound on the middle column, one end of the first coil is a 1 st end, the other end of the first coil is a 2 nd end, the first end of the second coil is a 4 th end, and the second end of the second coil is a 5 th end; winding N₁(i.e., the number of winding turns) constitutes the inverter-side inductor, winding N₂Form a grid side inductor); the third coil and the fourth coil of the first winding are wound on the side column firstly (forming N)₃) Then wound around the other side column (also forming N)₃) And finally a third coil wound on the upper part of the center pillar and a fourth coil wound on the lower part of the middle pillar, it being noted that: in the center leg portion, two coils (i.e., N) of the first winding₂) The coil is positioned at the bottom of the two coils of the second winding; winding N with side pole₃The common-mode EMI filter inductor is used, the side column winding comprises two side columns, and the leakage inductance of the common-mode EMI filter inductor is used as a differential-mode EMI filter inductor. Under the excitation of the common mode noise signal, the magnetic paths of the magnetic circuit are as shown in fig. 6, the magnetic fluxes on the left and right side columns are mutually enhanced, and the magnetic fluxes on the center column are mutually offset; under the excitation of the differential mode signal, as shown in fig. 7, the magnetic fluxes on the side posts are mutually cancelled, and the magnetic fluxes on the middle posts are mutually enhanced, so that the common mode and harmonic suppression performance of the side post winding and the middle post winding can be improved. In addition, the air gap is designed on the center pillar, so that the coupling coefficient of the left and right pillar windings can be controlled;

wherein l_gIndicating the air gap length.

According to the above conclusion, it can be seen that: when a magnetic circuit under common-mode excitation is analyzed, the winding on the center pillar is not required to be considered; when a magnetic circuit under differential mode excitation is analyzed, the windings on the side columns do not need to be considered; therefore, the common and differential mode magnetic circuits can be simplified to the structures shown in fig. 8 and 9, respectively. In order to analyze the coupling characteristics between the windings in detail, a common-mode equivalent magnetic circuit model and a differential-mode equivalent magnetic circuit model can be further drawn according to fig. 7 and 8.

Referring to fig. 10 and 11, fig. 10 and 11 are respectively a common mode equivalent magnetic circuit model and a differential mode equivalent magnetic circuit model, and fig. 10 shows: the common-mode equivalent magnetic circuit model comprises 2I_CMN₃2R_c14, R_c22R_c31, R_gFirst I of_CMN₃The positive electrode of the anode is sequentially connected with the first R_c1First R_c2First R_c3、R_g、Second R_c3A second R_c2Then returning to the negative electrode to form a first loop, and a third R_c2Second I_CMN₃A second R_c1The fourth R_c2The three are connected in series and then are connected with the first R_c3、R_g、Second R_c3Three are connected in parallel, it should be noted that the third R_c2Is connected with the second I_CMN₃The negative electrode of (1); in fig. 11 are shown: the differential mode equivalent magnetic circuit model comprises 1I_CMN₃2R_c14, R_c22R_c31, R_g，I_CMN₃The positive electrode of the anode is sequentially connected with the first R_c1First R_c2First R_c3、R_g、Second R_c3A second R_c2Then returning to the negative electrode to form a first loop, and a third R_c2A second R_c1The fourth R_c2The three are connected in series and then are connected with the first R_c3、R_g、Second R_c3The three are connected in parallel; and then specific analysis and calculation are carried out according to the ohm law of the magnetic circuit. Wherein I_CMN₃And I_DMN₁(or I)_DMN₂) Are respectively a winding N₃And N₁(or N)₂) Respectively generating a common mode magnetic potential and a differential mode magnetic potential; r_c1、R_c2、R_c3And R_gAre respectively an edgeEquivalent magnetic resistance of the air gaps of the column, the magnetic yoke, the center column and the center column. It can be seen that the common mode coupling coefficient is related to the designed air gap length on the center leg. Therefore, the differential mode windings on the center pillars are fully coupled, and the coupling coefficient is 1. Expressions of common-mode inductance and harmonic filter inductance can be obtained and are respectively expressed as the formula (1) and the formula (2), wherein R_S，CMAnd R_S，DMThe self-inductance magnetic resistances of the side column winding (under common-mode excitation) and the middle column winding (under differential-mode excitation) are respectively expressed by the expressions shown in the above expression (3) and expression (4); m_CMRepresenting the mutual inductance between any two windings on the common-mode excitation lower side column; k_M，CMIs the common mode mutual inductance. For the corresponding partial reluctance R₁、R₂、R_c1、R_c2、 R_c3And R_gIs as defined in the above formula (5), wherein l_s、l_yAnd l_cThe lengths of the side pole magnetic circuit, the yoke and the center pole magnetic circuit (upper/lower portions) are respectively shown; a. the_s、A_yAnd A_cRespectively showing the cross-sectional areas of the side column, the magnetic yoke and the center column of the magnetic core; mu.s₀And mu_rRespectively, the vacuum permeability and the relative permeability of the core used.

The common mode inductance coupling coefficient expression is as the above expression (6), which is closely related to the center pillar air gap length, and this is also a key factor to be considered in the center pillar air gap design. In order to better improve the common-mode rejection performance of the side pole winding, the common-mode inductive coupling coefficient is preferably greater than or equal to 0.9. On the other hand, however, the king post air gap directly increases the reluctance on the king post, and the larger the air gap length, the larger the reluctance, which results in the more turns needed to achieve the same harmonic filter inductance. Furthermore, in order to satisfy the requirement that the core does not reach saturation, the total number of turns of the winding on the center post should satisfy the above formula (7), wherein B_maxIs the saturation flux density of the magnetic core; a. the_eIs the effective cross-sectional area of the core; i is₂Is the effective value of the current on the network side under the rated output power. Therefore, it is necessary to determine the maximum value of the common mode coupling coefficient and the number of turns of the winding on the center leg reasonably by comprehensively considering the common mode coupling coefficient, and to satisfy the formula (7) for the number of turns of the center leg winding required for the harmonic inductance even if the common mode coupling coefficient is high (0.9 or more) to prevent the magnetic core from being damagedSaturation, the performance of the inductor is guaranteed.

Wherein phi is_DMThe total magnetic flux generated for the differential mode excitation, N represents the total number of differential mode coils, and I represents the differential mode current value (calculated with the fundamental current value, verified).

In addition, through measurement, the length of the PCB (circuit board) of the traditional single-phase harmonic filter and the traditional electromagnetic interference filter which do not pass through the magnetic integration technology is about 15 cm; the length of the PCB (circuit board) integrated with the single-phase harmonic filter and the electromagnetic interference filter by the magnetic integration technology is about 10 cm.

It should be noted that the above-mentioned numbers of the embodiments of the present invention are merely for description, and do not represent the merits of the embodiments. And the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, apparatus, article, or method. The term "comprising", without further limitation, means that the element so defined is not excluded from the group of processes, apparatuses, articles or methods that include the element.

Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) as described above and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.