CN202996475U - Integrated EMI (electro-magnetic interference) filter for improving noise suppression performance by optimizing grounding winding layout - Google Patents

Abstract

The utility model discloses an integrated EMI (electro-magnetic interference) filter for improving noise suppression performance by optimizing grounding winding layout. The integrated EMI filter comprises an E-type magnetic core, a first I-type magnetic core, a second I-type magnetic core used for increasing difference-mode leakage inductance, and two common-mode winding units identical in structure, and the two common-mode winding units are symmetrically arranged on two sides of the second I-type magnetic core. On the basis of studying of characteristics of element integration and various coupling actions among elements and by optimizing grounding winding layout of the integrated EMI filter, equivalent shunt capacitance of common-mode inductance is effectively eliminated with lower structural complexity and processing difficulty. By comparing high-frequency performances under modes of reverse coupling, forward coupling and bidirectional coupling, a conclusion that a bidirectional-coupled grounding winding structure can improve high-frequency suppression capacity of common-mode noise to the greatest extent is drawn; processing and testing of the integrated EMI filter are completed by performing quantitative analysis to the design process by introducing an equivalent circuit and by stimulating filter effect through accurate field simulation software.

Description

Optimize ground connection winding layout to improve the integrated EMI filter of noise suppressed performance

Technical field

The utility model relates to the technical field of filter, particularly high-performance, high integration, can satisfy small-sized, broadband, integrated technique designing requirement, can be applied to the electromagnetic interface filter in power electronic system.

Background technology

Along with the operating frequency of power semiconductor improves constantly, power electronic equipment is begun to receive much attention by the impact of its electromagnetic interference that causes on peripheral equipment towards the future development of high density, miniaturization.

Conventional filter adopts discrete component to realize, yet there are some problems in the electromagnetic interface filter of realizing with discrete component.At first, because there is inevitable parasitic parameter in discrete passive component, equivalent parallel electric capacity (Equivalent Parallel Capacitance such as common mode choke, EPC) and the equivalent series inductance of electric capacity (Equivalent Series Inductance, ESL), effectively the filtering frequency range is only limited in the scope of several megahertzes usually.Secondly, the ghost effect that causes due to the filter topologies design will further affect the performance of high band, therefore need abundant design experiences.Again, the discrete component electromagnetic interface filter comprises more component number, and they need to make therefore respectively to separate on function and structure, and this just requires more material type and Production Time.At last, different elements has different types, original paper value, size and profile, need simultaneously the connecting line space that provides larger, so space availability ratio is lower.In order to improve high frequency characteristics, to reduce physical size, reduce production costs and reach the integrated of structure, function and manufacturing process, proposed the Planar integration electromagnetic interface filter and be used for saving processing cost and time.Therefore significant for the research of integrated EMI filter.

When electromagnetic interface filter was operated in high frequency, parasitic parameter became the key factor that affects filtering performance.Due to each branch road existence resonance frequency and interelement coupling effect separately, the high frequency performance of filter is with variation, and the insertion loss that shows as filter reduces, cisco unity malfunction in the 150kHz-30MHz scope that conducted interference is considered.Therefore, carry out the extraction of integrated EMI filter parasitic parameter, and eliminate these parasitic parameters, to designing high performance filter, the conducted interference that reduces in electronic equipment is significant.

The utility model content

The shortcoming that the purpose of this utility model is to overcome prior art provides a kind of electromagnetic interface filter that can effectively eliminate the equivalent parallel electric capacity of common mode inductance with not enough.

In order to achieve the above object, the utility model is by the following technical solutions:

The utility model is optimized ground connection winding layout to improve the integrated EMI filter of noise suppressed performance for passing through, comprise E type magnetic core, an I type magnetic core and the 2nd I type magnetic core that is used for increasing the differential mode leakage inductance, the common mode winding element that also comprises two same structures, described common mode winding element is symmetricly set on the both sides of the 2nd I type magnetic core, it is five layers that described common mode winding element is divided into, upper strata common mode inductance conductor layer from top to bottom successively, low dielectric constant, lower floor's common mode inductance conductor layer, high-K dielectric layer, and grounding conductor layer.

Preferably, described upper strata common mode inductance conductor layer, lower floor's common mode inductance conductor layer and grounding conductor layer all adopt copper spiral winding configuration.

Preferably, the adjacent two general minimum process precision of coil-span of winding are 0.5mm, but consider area constraints, and spacing is also unsuitable excessive.

Preferably, described upper strata common mode inductance conductor layer, lower floor's common mode inductance conductor layer are connected with inner by through hole.

Preferably, described low dielectric constant is the kapton film of dielectric constant 3.6.

Preferably, the thickness of described low-k dielectric layer should considered under the spatial limitation prerequisite as far as possible greatly as 0.05mm.

Preferably, described high-K dielectric layer should consider that space and the restriction of common mode capacitance size are 84 ceramic substrate as relative dielectric constant.

Preferably, described high-K dielectric layer thickness should consider that space and the restriction of common mode capacitance size are as being 0.15mm.

Preferably, the thickness of each common mode winding element is 0.3mm, and conductor width is 1.2mm.

Preferably, fill with medium with low dielectric constant kapton between the conductor of common mode winding element levels and magnetic core.

The utility model has following advantage and effect with respect to prior art:

1, the utility model the characteristics of having studied component integration and between various couplings bases on, by optimizing integrated EMI filter ground connection winding layout, thereby with simpler structure, less complexity and difficulty of processing have effectively been eliminated the equivalent parallel electric capacity of common mode inductance.

2, the utility model passes through three kinds of coupled modes between ground connection winding and inductor winding: the high frequency performance contrast of reverse coupled, forward coupling and bidirectional coupled mode, drawn the conclusion that bidirectional coupled ground connection winding construction can at utmost promote the high-frequency suppressing ability of common-mode noise, introduce simultaneously equivalent electric circuit design process has been carried out quantitative analysis, and utilize an accurate simulation software that filter effect is simulated, completed processing and the test of integrated EMI filter.

3, the utility model is compared with the method for the embedding grounding conductor layer of existing Switching Power Supply integrated EMI filter parasitic capacitance technology for eliminating, has the conductor number of plies still less, thereby can reduce production costs and process time, be applicable to the noise suppressed of Switching Power Supply.

Description of drawings

Fig. 1 is the general structure schematic diagram of integrated EMI filter.

Fig. 2 is the left hemihedrism schematic cross-section of traditional integrated EMI filter.

Fig. 3 is the detailed decomposing schematic representation of each layer of common mode winding element.

Fig. 4 a is the upper strata inductor conductor floor map of common mode winding element in traditional integrated EMI filter.

Fig. 4 b is lower floor's inductor conductor floor map of common mode winding element in traditional integrated EMI filter.

Fig. 4 c is the ground conductor plane schematic diagram of common mode winding element in traditional integrated EMI filter.

Fig. 5 is the principle explanation of the equivalent electric circuit form of common mode inductance winding parasitic capacitance elimination.

Fig. 6 a is the floor map of reverse coupled ground connection winding.

Fig. 6 b is the floor map of forward coupling grounding winding.

Fig. 6 c is the floor map of bidirectional coupled ground connection winding.

Fig. 7 a is the left hemihedrism schematic cross-section that adopts the integrated EMI filter of reverse coupled ground connection winding.

Fig. 7 b is the left hemihedrism schematic cross-section that adopts the integrated EMI filter of forward coupling grounding winding.

Fig. 7 c is the left hemihedrism schematic cross-section that adopts the integrated EMI filter of bidirectional coupled ground connection winding.

Fig. 8 is the emulation insertion loss curve that adopts respectively three kinds of ground connection winding constructions.

Fig. 9 is the circuit diagram that uses in the EMI noise Simulation.

Figure 10 is the common-mode noise level curve of the integrated EMI filter of initial common-mode noise level curve and the related employing bidirectional coupled of the utility model ground connection winding.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the utility model is described in further detail, but execution mode of the present utility model is not limited to this.

Embodiment

Fig. 1 (a) is the general structure schematic diagram of traditional integrated EMI filter, be included as E type magnetic core 1, the one I type magnetic core 2, specification is E+PLT38-3E5, and initial relative permeability is 10000, is used for increasing the 2nd I type magnetic core 3 of differential mode leakage inductance, made by the FPC material, initial relative permeability is 9, also is included as two identical common mode winding elements 4,5, places in differential mode the 2nd I type magnetic core bilateral symmetry.Consider that it is the left-right symmetric structure that whole filter is faced the cross section, Fig. 2 has provided the schematic diagram of left hemihedrism cross section.Wherein to be divided into be five layers to common mode winding element 4,5, is followed successively by upper strata common mode inductance conductor layer 6, low dielectric constant 9, lower floor's common mode inductance conductor layer 7, high-K dielectric layer 10, grounding conductor layer 8, all conductor layers all adopt copper spiral winding configuration.Low dielectric constant 9 is 3.6 kapton film for relative dielectric constant, and thickness is 0.05mm.High-K dielectric layer 10 is 84 ceramic substrate for relative dielectric constant, thickness is 0.15mm, the low impedance path of the electric capacity that itself and two side conductors form when high frequency to be provided and between ground, it should be noted that simultaneously, consider safety factor, the size of current that flows through ground need to limit within the specific limits usually, and this is also that design is the major issue that needs consideration.Consideration for Power Limitation, upper strata common mode inductance conductor layer 6, lower floor's common mode inductance conductor layer 7 thickness are 0.3mm, conductor width is 1.2mm, space between the adjacent coils is 0.5mm, up and down common mode inductance conductor layer connects in inside by through hole, and the multi-layer helical inductance is conducive to realize enough large inductance value in limited area; Grounding conductor layer 8 thickness are 0.1mm.Same with medium with low dielectric constant kapton filling between the conductor of common mode winding element levels and magnetic core.

Fig. 4 a, Fig. 4 b, Fig. 4 c are respectively related three the conductor winding plane figures of common mode winding element, and wherein, the first port 11 is input, and the 3rd port one 3 is output, and the 6th port one 6 is left intact, and ground connection winding earth port is five-port 15; The second port one 2 is connected by through hole with the 4th port one 4, forms the double-layer spiral structure.

In order to illustrate by optimizing ground connection winding layout to eliminate the principle of common mode inductance parasitic capacitance, Fig. 5 has provided corresponding simple equivalent circuit, wherein ignored the impact of conductor losses and imperfect coupling, because the utility model has adopted high magnetic permeability planar magnetic core and good conductor, this being similar at 150kHz allows in the 30MHz band limits.C wherein _pThe parasitic capacitance that forms between expression common mode inductance winding, ground connection winding L ₃Expression, the lower floor common mode inductance winding 7 relative with the ground connection winding parallel used L ₂Expression wholely comprises bilevel common mode inductance winding and removes L ₂Remaining winding is partly used L ₁Expression, the coupling coefficient between them is used respectively k ₁, k ₂, k ₃Expression.In desirable coupling situation, k ₁=1, k ₂, k ₃=± 1, sign wherein is subjected to the control of coupling polarity, during the forward coupling, and k ₂=k ₃=1, during reverse coupled, k ₂=k ₃=-1.By the solution analysis that is coupled, can obtain illustrated decoupling zero circuit, then it is done the conversion of Y-Δ can obtain π type equivalent electric circuit.Series element admittance parameter wherein:

$Y_a=\frac{1-{\mathrm{\&omega;}}^2[({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1\mathrm{Decoup}}+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2\mathrm{Decoup}})C_p+{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_{3\mathrm{Decoup}}{C}_g/2]}{\mathrm{j\&omega;}({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1\mathrm{Decoup}}+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2\mathrm{Decoup}})}$

（ ${\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1\mathrm{Decoup}}={\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+k_1\sqrt{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}+k_2\sqrt{L_1{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_3}+k_3\sqrt{L_2{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_3},$ ${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_{2\mathrm{Decoup}}={\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+k_1\sqrt{L_1{L}_2}-k_2\sqrt{L_1{L}_3}-k_3\sqrt{L_2{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_3},$

${\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600041.png"\; state="\{\{state\}\}">L</figure-callout>}}_{3\mathrm{Decoup}}=L_3-k_1\sqrt{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002609212600012.png,HDA00002609212600031.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}+k_2\sqrt{L_1{L}_3}-k_3\sqrt{L_2{L}_3}$ ）

Be pure inductance for making series arm, the molecule that requires the admittance expression formula is 1.Can obtain thus the general condition of the parasitic capacitance technology for eliminating that the utility model proposes:

When adjusting ground connection winding layout so that the size of common mode capacitance when satisfying the desired value of general condition, just can eliminate the impact of parasitic capacitance, finally obtain a π type filter circuit, compare original L-type circuit, preposition shunt capacitance branch road can further improve the high frequency performance of filtering.

Three kinds of ground connection windings after improvement are layout and earth point position such as Fig. 6 a respectively, Fig. 6 b, shown in Fig. 6 c, their reverse coupled between corresponding ground connection winding current and common mode inductor winding electric current, forward couplings and both are combined three kinds of situations that consist of bidirectional coupled respectively.

Fig. 7 a, Fig. 7 b, Fig. 7 c are respectively and adopt three kinds of corresponding left hemihedrism cross sectional representation of ground connection winding, and the common mode inductance size is 4.5mH.Wherein reverse coupled ground connection winding live width is unified is 1.2mm, and adjusting length is 37.8mm, and the common mode capacitance size is 2 * 1.56nF.Forward coupling grounding winding live width 1.65mm and 4.3mm, adjusting length is 30.05mm, the common mode capacitance size is 2 * 3.28nF.In a kind of bidirectional coupled form that dual mode is combined that further proposes, the narrower winding width in outside of forward coupling is 0.8mm, and the wider winding width in the inside of reverse coupled is 1.8mm.Optimization length is 7.5mm, and the common mode capacitance size is 2 * 2.12nF.

Adopt Ansoft HFSS software respectively the integrated EMI filter of three kinds of structures to be carried out emulation, the insertion loss of gained as shown in Figure 8.As a reference, the filter that adopts traditional ground connection winding construction has also been carried out emulation.Can find out, near the resonance frequency of the ground connection winding layout postfilter after employing is optimized moves to 5MHz from 250kHz, simultaneously, compare three kinds of ground connection winding constructions, adopt the insertion loss of ground connection winding after 10MHz of bidirectional coupled form to increase 20dB, therefore have the more noise inhibiting ability in broadband.

Fig. 9 shows the complete circuit schematic diagram that the EMI noise is carried out emulation.Common-mode noise level after Figure 10 has listed the initial common-mode noise level that utilizes Pspice emulation and adopted bidirectional coupled ground connection winding electromagnetic interface filter.Can find out that filter that the utility model proposes after the parasitic capacitance of having eliminated inductor winding, has good noise inhibiting ability at 150kHz in the frequency band range of 30MHz.

Above-described embodiment is the better execution mode of the utility model; but execution mode of the present utility model is not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present utility model and principle, substitutes, combination, simplify; all should be the substitute mode of equivalence, within being included in protection range of the present utility model.

Claims (10)

1. optimize ground connection winding layout to improve the integrated EMI filter of noise suppressed performance for one kind, comprise E type magnetic core, an I type magnetic core and the 2nd I type magnetic core that is used for increasing the differential mode leakage inductance, it is characterized in that, the common mode winding element that also comprises two same structures, described common mode winding element is symmetricly set on the both sides of the 2nd I type magnetic core, it is five layers that described common mode winding element is divided into, upper strata common mode inductance conductor layer from top to bottom successively, low dielectric constant, lower floor's common mode inductance conductor layer, high-K dielectric layer, and grounding conductor layer.

2. optimization ground connection winding layout according to claim 1 is to improve the integrated EMI filter of noise suppressed performance, it is characterized in that, described upper strata common mode inductance conductor layer, lower floor's common mode inductance conductor layer and grounding conductor layer all adopt copper spiral winding configuration.

3. optimization ground connection winding layout according to claim 2 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, the adjacent two coil-span minimum process precision of copper spiral winding are 0.5mm.

4. optimization ground connection winding layout according to claim 1 and 2 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, described upper strata common mode inductance conductor layer, lower floor's common mode inductance conductor layer connect in inside by through hole.

5. optimization ground connection winding layout according to claim 1 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, described low dielectric constant is the kapton film of dielectric constant 3.6.

6. optimization ground connection winding layout according to claim 5 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, the thickness of described low dielectric constant is 0.05mm.

7. optimization ground connection winding layout according to claim 1 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, described high-K dielectric layer is the ceramic substrate of relative dielectric constant 84.

8. optimization ground connection winding layout according to claim 7 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, described high-K dielectric layer thickness is 0.15mm.

9. optimization ground connection winding layout according to claim 1 to improve the integrated EMI filter of noise suppressed performance, is characterized in that, the thickness of each common mode inductance winding is 0.3mm, and conductor width is 1.2mm, and the thickness of ground connection winding is 0.1mm.

10. optimization ground connection winding layout according to claim 1 is to improve the integrated EMI filter of noise suppressed performance, it is characterized in that upper strata common mode inductance conductor layer and magnetic core and about filling with medium with low dielectric constant kapton between the common mode inductance conductor layer of the 2nd I type magnetic core symmetric position and magnetic core.

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