U.S. patent application number 12/903243 was filed with the patent office on 2011-04-07 for inductor topologies with substantial common-mode and differential-mode inductance.
This patent application is currently assigned to Ford Global Technologies5. Invention is credited to Chingchi Chen, Michael Degner, Feng Liang.
Application Number | 20110080246 12/903243 |
Document ID | / |
Family ID | 38566702 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110080246 |
Kind Code |
A1 |
Chen; Chingchi ; et
al. |
April 7, 2011 |
INDUCTOR TOPOLOGIES WITH SUBSTANTIAL COMMON-MODE AND
DIFFERENTIAL-MODE INDUCTANCE
Abstract
An inductor includes a core that has a window. The core includes
a first core member and a second core member. A first winding is
coupled to the first core member and a second winding is coupled to
the second core member. A floating center leg is coupled between,
but not attached to, the first and second core members. The
floating center leg is conductively enabling flux flow between the
first core member and the second core member.
Inventors: |
Chen; Chingchi; (Ann Arbor,
MI) ; Degner; Michael; (Novi, MI) ; Liang;
Feng; (Canton, MI) |
Assignee: |
Ford Global Technologies5
|
Family ID: |
38566702 |
Appl. No.: |
12/903243 |
Filed: |
October 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11533992 |
Sep 21, 2006 |
|
|
|
12903243 |
|
|
|
|
Current U.S.
Class: |
336/212 |
Current CPC
Class: |
H01F 3/12 20130101; H01F
38/023 20130101; H03H 7/427 20130101; H01F 2017/0093 20130101; H01F
27/38 20130101; H03H 2001/005 20130101; H01F 2017/065 20130101;
H01F 37/00 20130101; H01F 3/14 20130101 |
Class at
Publication: |
336/212 |
International
Class: |
H01F 27/24 20060101
H01F027/24 |
Claims
1. An inductor comprising: a core having a window and comprising; a
first core member; a second core member; and lateral core members
disposed between said first and second core members a first winding
coupled to said first core member; a second winding coupled to said
second core member; and at least one floating center leg coupled
between but not attached to said core, said floating center leg
conductively enabling flux flow between said first core member and
said second core member such that both common-mode noise and
differential mode noise are simultaneously filtered.
2. An inductor as in claim 1 wherein said at least floating center
leg has at least one pair of gaps between said floating center leg
and said core.
3. An inductor as claimed in claim 2 wherein said at least one pair
of gaps is filled with a predetermined material.
4. An inductor as in claim 1 wherein said core is a continuous
core.
5. An inductor as in claim 1 wherein said at least one floating
center leg is a dividing member between said first core member and
said second core member.
6. An inductor as in claim 5 wherein said core further comprises at
least one break.
7. An inductor as in claim 6 wherein said at least one break is
filled with a predetermined material for adjusting a permeability
of said core.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending application
Ser. No. 11/533,992, filed on Sep. 21, 2006, incorporated by
reference herein.
TECHNICAL FIELD
[0002] The present invention relates to vehicle and non-vehicle
electronic and electrical systems and components. More
particularly, the present invention is related to inductor
topologies for common-mode and differential-mode filtering circuits
and the like.
BACKGROUND OF THE INVENTION
[0003] A variety of power converters are used throughout industry.
Power converters are often utilized in electronic circuits for
direct current (DC) or alternate current (AC) conversion to supply
power to electric motors. Such conversion is performed on hybrid
electric vehicles, fan drives, washing machines, refrigerators, and
other various machines and equipment to improve efficiency and
performance, as well as to minimize noise.
[0004] Certain electronic circuits exhibit high switching speeds.
At high switching speed, the electronic circuits generate
common-mode (CM) and differential-mode (DM) electromagnetic
interference (EMI) noises. Thus, CM and DM filters are incorporated
to remove such noise. The theoretically simplest filter topologies
include capacitors and inductors that are without mutual-couplings
between windings. However, in actual implementation, the inductors
are normally with mutually coupled windings to minimize inductor
size. Depending on the coupling polarity to the inductors and the
number of inductors used, the CM or DM noises can be effectively
blocked. Traditionally, a first inductor is used to filter CM
noises and a second inductor is used to filter DM noises. A single
traditional inductor is not effective in simultaneously filtering
both CM and DM noises, due to the structure thereof.
[0005] There is a desire to further reduce the circuit size, cost,
complexity, and weight associated with CM and DM inductor
filtering. Thus, there is a need for an improved technique of
providing CM and DM inductor filtering.
SUMMARY OF THE INVENTION
[0006] In one embodiment of the present invention an inductor is
provided that includes a core with a window. The core includes a
first core member and a second core member. A first winding is
coupled to the first core member and a second winding is coupled to
the second core member. One or more cross-member(s) are coupled at
least partially across and are conductively enabling flux flow
between the first core member and the second core member.
[0007] In another embodiment of the present invention an electronic
circuit is provided that includes an input terminal, an inductor,
and an output terminal. The inductor is coupled to the input
terminal and has only a single inductive core. The inductor is
coupled to filter both common-mode noise and differential-mode
noise. The output terminal is coupled to and receives filtered
common-mode and differential-mode current from the inductor.
[0008] The embodiments of the present invention provide several
advantages. One advantage provided by an embodiment of the present
invention is a circuit having a single inductor that provides both
common-mode and differential-mode filtering of electromagnetic
interference noises.
[0009] The present invention is versatile in that it provides
configurations that may be utilized and varied among a diverse
range of applications, electronic circuits, and industries.
[0010] In addition, the present invention reduces the size, weight,
and complexity of an electromagnetic interference filtering circuit
and as such the costs associated therewith.
[0011] The present invention itself, together with further objects
and attendant advantages, will be best understood by reference to
the following detailed description, taken in conjunction with the
accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a more complete understanding of this invention
reference should now be had to the embodiments illustrated in
greater detail in the accompanying figures and described below by
way of examples of the invention wherein:
[0013] FIG. 1 is a schematic view of a traditional electronic
circuit incorporating common-mode and differential-mode filtering
with inductors having single-coupled windings;
[0014] FIG. 2 is a schematic view of a traditional electronic
circuit incorporating common-mode and differential-mode filtering
with inductors having dual-coupled windings;
[0015] FIG. 3 is a side view of a traditional inductor having a
single window and a single winding;
[0016] FIG. 4 is a side view of another traditional inductor a pair
of windows and a single winding;
[0017] FIG. 5 is a side view of another traditional inductor having
a single window and a pair of windings;
[0018] FIG. 6 is a sample electronic circuit incorporating a
dual-mode filtering inductor in accordance with an embodiment of
the present invention;
[0019] FIG. 7A is a side magnetic flux flow representation of a
dual-mode filtering inductor in accordance with an embodiment of
the present invention;
[0020] FIG. 7B is a schematic view of a magnetic equivalent circuit
of the dual-mode filtering inductor described with respect to FIG.
7A.
[0021] FIG. 8 is a perspective view of a dual-mode filtering
inductor in accordance with an embodiment of the present
invention;
[0022] FIG. 9 is a side view of another dual-mode filtering
inductor incorporating a single non-wound center leg in accordance
with another embodiment of the present invention;
[0023] FIG. 10 is a side schematic view of a magnetic equivalent
circuit of the dual-mode filtering inductor of FIG. 9;
[0024] FIG. 11 is a side view of another dual-mode filtering
inductor incorporating a core having a split center leg in
accordance with another embodiment of the present invention;
[0025] FIG. 12 is a side view of another dual-mode filtering
inductor incorporating a core surrounded and floating center leg in
accordance with another embodiment of the present invention;
[0026] FIG. 13 is a side view of another dual-mode filtering
inductor having an outer flux flow enabling shell in accordance
with another embodiment of the present invention; and
[0027] FIG. 14 is a side view of another dual-mode filtering
inductor having core dividing center member in accordance with
another embodiment of the present invention.
DETAILED DESCRIPTION
[0028] In the following described FIGS. 1 and 2 typical common-mode
(CM) and differential-mode (DM) filter topologies are shown for the
reduction of electromagnetic interference (EMI) noise emission.
FIG. 1 illustrates a simple filter topology that includes
capacitors and inductors without mutually coupled windings. FIG. 2
illustrates a filter topology with inductors that have mutually
coupled windings.
[0029] Referring now to FIG. 1, a schematic view of a traditional
electronic circuit 10 that incorporates CM and DM filtering, with
inductors 12 that have single-coupled windings, is shown. The
circuit 10 includes an EMI source circuit 16 and a pair of
inductor-based filtering circuits, namely, a DM filtering circuit
18, and a CM filtering circuit 20.
[0030] The EMI source circuit 16 has a CM source 22, which
represents CM EMI noise generated by EMI circuit 16, and a pair of
DM sources 24, 26, which represent DM EMI noise generated by EMI
circuit 16. The CM source 22 has a CM terminal 28 and a ground
terminal 30. The EMI source circuit may be in the form of a power
source, a load, or a combination thereof. The DM sources 24, 26
have positive DM terminals 32 and negative DM terminals 34.
Impedance between the CM source 22 and the DM sources 24, 26 is
shown and represented as a first impedance Z.sub.1. The impedance
Z.sub.1 is coupled between the CM terminal 28 and a DM terminal 36,
which is in turn coupled between the DM sources 24, 26. Impedances
between the DM sources 24, 26 and the DM filtering circuit 18 are
shown and represented, respectively, as a second impedance Z.sub.2
and a third impedance Z.sub.3. The EMI circuit 16 has a terminal A
and a terminal B, which are coupled to the impedances Z.sub.2 and
Z.sub.3, respectively.
[0031] The DM filtering circuit 18 includes a DM capacitor C.sub.x
and a DM inductor L.sub.x. The DM capacitor C.sub.x is coupled to
and across the terminals A and B and in parallel to the DM sources
24, 26. The DM inductor L.sub.x has a single winding that is
coupled in series with the second impedance Z.sub.2 and post the DM
capacitor C.sub.x. The DM filtering circuit 18 has DM terminals C
and D that are coupled to the DM inductor L.sub.x and to the
terminal B and the DM capacitor C.sub.x.
[0032] The CM filtering circuit 20 includes a pair of CM capacitors
C.sub.y1 and C.sub.y2 and a pair of CM inductors L.sub.y1 and
L.sub.y2. The CM capacitors C.sub.y1 and C.sub.y2 are coupled in
series with each other and are coupled in parallel with the DM
capacitor C.sub.x. Each of the CM capacitors C.sub.y1 and C.sub.y2
is coupled to either the DM terminal C or the DM terminal D and to
ground. The first CM inductor L.sub.y1 is coupled to the DM
terminal C and to the first CM capacitor C.sub.y1, on a first end
40, and to a CM terminal E, on a second end 42. The second CM
inductor L.sub.y2 is coupled to the DM terminal D and to the second
CM capacitor C.sub.y2, on a first end 44, and to a CM terminal F,
on a second end 46. The CM terminals E and F may be input terminals
or output terminals and may be coupled to a load, a power source,
or a combination thereof. The location of the DM filter 18 and the
CM filter 20 may be swapped or interchanged. In other words, the CM
filter 20 may be directly connected to the circuit 16 and the DM
filter 18 may be connected between the CM filter 20 and the
terminals E, F.
[0033] Referring now to FIG. 2, a schematic view of a traditional
electronic circuit 10' that incorporates CM and DM filtering, with
inductors 50 that have dual-coupled windings, is shown. The
electronic circuit 10' is similar to the electronic circuit 10.
However, the single winding DM inductor L.sub.x is replaced with a
dual-winding DM inductor L.sub.x' and the DM filtering circuit 18'
is configured as such. The inductor L.sub.x' has a first
differential inductor terminal 52 that is coupled to the terminal
A, a second differential inductor terminal 54 that is coupled to
the DM terminal B, a third differential inductor terminal 56 that
is coupled to the DM terminal C, and a fourth differential inductor
terminal 58 that is coupled to the terminal D. The first terminal
52 and the third terminal 56 are associated with a first
differential winding 60. The second terminal 54 and the fourth
terminal 58 are associated with a seconding differential winding
62. Also, the CM inductors L.sub.y1 and L.sub.y2 are replaced with
a single dual-winding CM inductor L.sub.y' and the CM filtering
circuit 20' is configured as such. The CM inductor L.sub.y' has a
first common winding 63 that is coupled between the terminals C and
E and a second common winding 65 that is coupled between the
terminals D and F. Terminals 67 and 69 of the CM inductor L.sub.y'
are coupled to the DM terminals C and D, respectively. The
electronic circuit 10' also includes a load circuit 51 with DM load
impedances Z.sub.DM and CM load impedances Z.sub.CM. Similarly, the
location of the DM filter 18 and the CM filter 20 may be
interchanged. In other words, the CM filter 20 may be connected to
the circuit 16 and the DM filter 18 may be connected between the CM
filter 20 and the terminals E, F.
[0034] Referring now to FIGS. 1 and 2, in which CM and DM noise
conduction is shown. CM noise is conducted directly from the CM
source 22 to the terminals E and F on all lines, or through and
inward from highest potential and lowest potential branches, of the
electronic circuits 10 and 10'. The conduction of the CM noise is
represented by the CM noise lines 64. DM noise is conducted in a
current loop like fashion from the negative or lower potential
points in the electronic circuits 10 and 10' to the positive or
higher potential points in the electronic circuits 10 and 10'. The
conduction of the DM noise is represented by the DM noise lines
66.
[0035] Although the combined sizes of inductors L.sub.x' plus
L.sub.y' are smaller in size than the sum of inductors L.sub.x,
L.sub.y1, and L.sub.y2, they are similar in that they are each only
effective in blocking either CM or DM noises. The coupling polarity
of the mutual winding inductors determines the filtering
characteristics of that inductor or whether the inductor is a CM or
DM filtering inductor.
[0036] Referring now also to FIGS. 3-5, in which side views of
traditional inductors are shown. FIGS. 3-5 are herein included as
illustrated examples along with the following explanations
associated therewith that provides reasons for which traditional
inductors are incapable of exhibiting both CM and DM filtering
characteristics. In FIGS. 3 an inductor 70 that has a continuous
core 71 having a single window 72 and a single winding 74 is shown.
In FIG. 4 an inductor 75 that has a continuous core 76 having two
windows 78 and a single winding 80 is shown. The structures of the
inductors 70 and 75 of FIGS. 3 and 4 provide only DM filtering. The
structures are incapable of blocking CM noises since they have only
a single winding. On the other hand, the dual-winding inductor 82
of FIG. 5 can be coupled to perform as either an effective CM or a
DM filtering device, but not simultaneously. Note also that the
presence of multiple windings does not imply the ability to block
both DM and CM noises. Dual-winding configurations of the
embodiments of the present invention are provided below that
exhibit both DM and CM noise filtering characteristics.
[0037] The dual-winding inductor 82 includes terminals c, d, e, and
f and may serve as a two-terminal DM inductor or as a four-terminal
DM inductor. To serve as a two-terminal DM inductor, the inductor
terminals d and e are connected together, while the inductor
terminals c and f serve as the external terminals. To serve as a
four-terminal DM inductor, the inductor terminals c, d, e, and f
are mapped, for example, to the terminals A, D, C, and B,
respectively, of FIG. 2. Under this arrangement, the DM current
induces superimposed magneto-motive forces (mmfs) with high core
flux and inductance. On the other hand, the CM current through the
windings 84 of the dual-winding inductor 82 induces mutually
canceling mmfs, therefore, with low actual flux and inductance.
[0038] To perform as a CM inductor, the dual-winding inductor 82 is
configured and serves as a CM choke. In comparison with the above
four-terminal DM inductor approach, the polarity of one winding of
the dual-winding inductor is reversed. For example, the inductor
terminals d and f may be swapped to couple terminals B and D,
respectively. Under this arrangement, the dual-winding inductor 82
exhibits high CM inductance but low DM impedance.
[0039] The present invention overcomes the limitations of
traditional inductor approaches and is described in detail
below.
[0040] In each of the following figures, the same reference
numerals are used to refer to the same components. The present
invention may apply to automotive, aeronautical., nautical, and
railway applications, as well as to other applications in which
substantial CM and DM filtering is desired simultaneously. The
present invention may be applied in commercial and non-commercial
settings. The present invention may be applied in appliances, in
trailers, off-highway equipment, in auxiliary equipment, in
communication systems, and in a variety of other applications or
settings,
[0041] Also, a variety of other embodiments are contemplated having
different combinations of the below described features of the
present invention, having features other than those described
herein, or even lacking one or more of those features. As such, it
is understood that the invention can be carried out in various
other suitable modes.
[0042] In the following description, various operating parameters
and components are described for one constructed embodiment. These
specific parameters and components are included as examples and are
not meant to be limiting.
[0043] Referring now to FIG. 6, a sample electronic circuit 100
incorporating a dual-mode filtering inductor 102 in accordance with
an embodiment of the present invention is shown. The electronic
circuit 100 includes an EMI source circuit 104, a dual-mode
filtering circuit 106, and terminals E' and F', which may perform
as output terminals and be coupled to one or more drivers 110 and,
respective one or more motors 112 (only one driver and motor are
shown), as shown. The terminals E and F may, in addition or in the
alternative to be coupled to a load, or be coupled to a power
source. Also, the terminals E and F may be used as input terminals,
depending upon the application. Note that the arrangement,
coupling, and configuration of the components of the electronic
circuit 100 is provided only as an example, an infinite number of
other electrical circuit arrangements, couplings, and
configurations may be formed utilizing a dual-mode filtering
inductor. Although the electronic circuit is shown in the form of a
DC dual-filtered drive circuit, and as such the dual-mode inductor
102 is described in respect thereto, the dual-mode inductor 102 may
be utilized and incorporated into other electronic circuits known
in the art that have a need for DM and CM filtering. Also, an
inductor symbol is provided in FIG. 6 to represent the use of a
dual-mode filtering inductor. The provided symbol does not refer to
one particular dual-mode filtering inductor, but rather signifies
that any one of the dual-mode filtering inductors described herein
or devised via the teachings herein may be utilized in the
electronic circuit 100.
[0044] The EMI circuit 104 includes a CM noise source 116, which
represents the CM noise generated by the EMI circuit 104. The CM
source 116 has a supply terminal 120 and a ground terminal 124. The
supply terminal 120 is coupled in series with a first impedance
Z.sub.1'. The ground terminal 124 is coupled to the ground 125. The
first impedance Z.sub.1' has first impedance terminals 126 and 128.
The first impedance terminal 126 is coupled to the supply terminal
120. The first impedance terminal 128 is coupled to a pair of DM
noise sources 130, 132, which represent the DM noise conducted in
the EMI circuit 104. The first DM source 130 has first DM terminals
134 and 136. The first DM terminal 136 is coupled to the first
impedance terminal 128. The second DM source 132 has second DM
terminals 138 and 140. The second DM terminal 138 is coupled to the
first impedance terminal 128. The first DM terminal 134 is coupled
to a source terminal A' through impedance Z2. The second DM
terminal 140 is coupled to a source terminal B' through impedance
Z3.
[0045] A second impedance Z2' and a third impedance Z3' are coupled
to the DM sources 130, 132. The second impedance Z2' has second
impedance terminals 142 and 144. The third impedance Z3' has third
impedance terminals 146 and 148. The second impedance terminal 142
is coupled to the first DM source terminal 134. The third impedance
terminal 146 is coupled to the second DM source terminal 140.
[0046] The dual-mode filtering circuit 106 includes CM and DM
capacitors and the dual-mode inductor 102. A differential capacitor
C.sub.x' is coupled in parallel with the DM sources 130, 132 and
between the second impedance terminal 144 and the third impedance
terminal 148 on the terminals A' and B'. A pair of CM capacitors
C.sub.y1' and C.sub.y2' are coupled in series with each other and
combined in parallel to the DM capacitor C.sub.x'. The first CM
capacitor C.sub.y1' is coupled between the terminal A' and ground
125. The second CM capacitor C.sub.y2' is coupled between ground
125 and the terminal B'.
[0047] The dual-mode inductor 102 has and/or is coupled to inductor
terminals s, u, t, and v. The inductor terminals s and u are
coupled to the terminals A' and B', respectively. The inductor
terminals t and v are coupled to the electronic circuit terminals
E' and F'. Terminals E' and F' may perform as input or output
terminals, depending upon the application.
[0048] In the following FIGS. 7A and 7B, inductor topologies and
representations are provided for the example inductors of FIGS.
8-14.
[0049] Referring now to FIGS. 7A and 7B, a side magnetic flux flow
representation of a dual-mode inductor and a side schematic view of
a magnetic equivalent circuit thereof are shown. The dual-mode
inductor has a core 150 with wound core members 151, 152 and
lateral members 153, 154. A pair of windings 155, 156 are wound on
the wound core members 151, 152, respectively. A pair of cross flux
flow members 157, 158 are coupled between diagonally opposite ends
of the wound core members. The windings 155, 156 have terminals s',
t', u', and v', which may be mapped to terminals s, t, u, and v of
FIG. 6, respectively.
[0050] With two windings and two cross-members, the dual-mode
inductor provides six magnetic internal flux paths P.sub.A,
P.sub.B, P.sub.C, P.sub.D, P.sub.E, and P.sub.F having associated
magnetic flux therein, represented and designated by .PHI..sub.A,
.PHI..sub.B, .PHI..sub.C, .PHI..sub.D, .PHI..sub.E, and
.PHI..sub.F. The first core member 151 performs as flux path
P.sub.A and has flux .PHI..sub.A, the second core member 152
performs as flux path P.sub.B and has flux .PHI..sub.B, the first
lateral member 153 performs as flux path P.sub.C and has flux
.PHI..sub.C, the second lateral member 154 performs as flux path
P.sub.D and has flux .PHI..sub.D, the first cross-member 157
performs as flux path P.sub.E and has flux .PHI..sub.E, and the
second cross-member 158 performs as flux path P.sub.F and has flux
.PHI..sub.F. FIG. 7B shows the equivalent magnetic circuit for the
dual-mode inductor, where the magneto-motive forces (mmfs) are
modeled as equivalent voltage sources and the core reluctances are
modeled as resistances. The equivalent voltage sources are
approximately equal to the product of the number of turns of the
windings on the core member of concern and the current through that
winding. The number of turns of the windings, for the dual-mode
inductor, are represented by N.sub.1 and N.sub.2 and the currents
are represented by I.sub.1 and I.sub.2. Each of the core members
151, 152, 153, 154 and the cross-members 157, 158 has an associated
reluctance R.sub.A, R.sub.B, R.sub.C, R.sub.D, R.sub.E, and
R.sub.F.
[0051] The flux through each branch or member in the dual-mode
inductor can be calculated by known circuit theories. The below
equations are provided assuming that the dual-mode inductor is
symmetrical, such that the number of windings N.sub.1 and N.sub.2
are equal, the reluctance R.sub.A is equal to the reluctance
R.sub.B, the reluctance R.sub.C is equal to the reluctance R.sub.D,
and the reluctance R.sub.E is equal to the reluctance R.sub.F. X
and Y component current variables I.sub.X and I.sub.Y are defined
based on combinations of winding currents I.sub.1 and I.sub.2 and
are provided by equations 1-4.
I X = I 1 + I 2 2 ( 1 ) I Y = I 1 + I 2 2 ( 2 ) I 1 = I X + I Y ( 3
) I 2 = I X - I Y ( 4 ) ##EQU00001##
[0052] When only the X flux current component exists, flux
.PHI..sub.Aflux .PHI..sub.B, flux .PHI..sub.C, and flux .PHI..sub.D
are equal, and flux .PHI..sub.E and flux .PHI..sub.F are equal to
zero. As such, flux .PHI..sub.X is provided by equation 5.
.PHI. X = NI X R A + R C ( 5 ) ##EQU00002##
From equation 5 the inductance L.sub.X can be determined by
equation 6.
L X = N .PHI. X I X = N 2 R A + R C ( 6 ) ##EQU00003##
On the other hand, when only the Y flux current component exists,
flux .PHI..sub.A, the inverse of flux .PHI..sub.B, flux
.PHI..sub.E, and flux .PHI..sub.F are equal, and flux .PHI..sub.C
and flux .PHI..sub.D are equal to zero. As such, flux .PHI..sub.F
is provided by equation 7 and the inductance L.sub.Y is provided by
equation 8.
.PHI. Y = NI Y R A + R E ( 7 ) L Y = N .PHI. Y I Y = N 2 R A + A E
( 8 ) ##EQU00004##
[0053] Equations 6 and 8 show that the inductances L.sub.X and
L.sub.Y can be determined independently. Also, if the currents
include the X and Y components, according to equations 3 and 4, the
windings 155, 156 are sized to handle the sum, or the difference,
of both components. Similarly, by combining equations 5 and 7, the
core paths P.sub.A and P.sub.B are sized to handle the sum, or the
difference, of the X and Y flux components. The core paths P.sub.C
and P.sub.D are sized to handle the X-component. The core paths
P.sub.E and P.sub.F are sized to pass the Y-component.
[0054] In certain cases, some of the core members may have zero or
infinite reluctance. For example, if the reluctance R.sub.C and the
reluctance R.sub.D are equal to zero, the topology of the dual-mode
inductor becomes as shown in FIGS. 9 and 10.
[0055] Note that in the following FIGS. 8-14 dual-mode filtering
inductors are provided that having a particular number of members,
windings, cross-members, and windows, these are examples only.
Other combinations may be formed having varying numbers of members,
windings, cross-members, and windows.
[0056] Referring now to FIG. 8, a perspective view of a dual-mode
filtering inductor 160 in accordance with an embodiment of the
present invention is shown. Although many of the features of the
inductor 160 are below described with "input" and "output"
designations, these are relative terms and depending upon the
application, the stated designations may be reversed. For example,
the winding terminals of the inductor that arc coupled to receive
input current determines which winding terminals are input
terminals and which are output terminals and, similarly, which core
member ends are input ends and which are output ends.
[0057] The dual-mode inductor 160 has a core 162 with a window 164.
In general, the core 162 includes multiple legs or members 166. For
the embodiment shown, the core 162 has a first wound core member
168 and a second wound core member 170. The first core member 168
and the second core member 170 are coupled to each other via a pair
of cross-members 172, 174. The cross-members 172, 174 are coupled
across the window 164 and provide an increased number of magnetic
flux flow paths over traditional inductors.
[0058] The first core member 168 has a first conductive element
winding 176 and a first core input end 167 and a first core output
end 169 on either side of the first winding 176. The second core
member 170 has a second conductive element winding 178 and a second
core input end 171 and a second core output end 173 on either side
of the second winding 178. The windings 176, 178 have terminals
s'', t'', u'', and v'', which may be mapped to terminals s, t, u,
and v of FIG. 6, respectively.
[0059] A pair of lateral core members 180, 181 is coupled between
the wound core members 168 and 170. The lateral members 180, 181
are integrally formed as part of the core 162, along with the wound
core members 168 and 170. The first lateral member 180 is coupled
to and between the first output end 167 and the second input end
171. The second lateral member 181 is coupled to and between the
first input end 169 and the second output end 173. Each of the
lateral members 180 and 181 has a break 182 such that the core 162
is split. The breaks 182 in the lateral members 180, 181 form the
four lateral elements M1, M2, M3, and M4. The elements M1 and M2
are coupled to the first core member 168 and the second core member
170. Similarly, the elements M3 and M4 are also coupled to the
first core member 168 and the second core member 170. A first gap
G1 exists between the elements M1 and M2. A second gap G2 exists
between the elements M3 and M4. The gaps G1 and G2 provide low
permittivity to prevent current saturation at full load. The gaps
G1 and G2 or other additional gaps may be of various sizes and
shapes, and may be filled with other materials to adjust the
effective permeability of the core or other characteristics. A few
other inductor dual-mode filtering examples having different gapped
configurations are provided below with respect to FIGS. 11-14.
[0060] The cross-members 172 and 174 may have a variety of
associated sizes, shapes, and configurations. The first
cross-member 172 is coupled to the diagonally opposite ends 167 and
173 via the elements M1 and M4. The second cross-member 174 is
coupled to the diagonally opposite ends 169 and 171 via the
elements M2 and M3.
[0061] The core 162, the core members 168 and 170, the elements
M1-M4, and the cross-members 172 and 174, and the windings 176, 178
may be formed of materials commonly associated with an inductor.
The core 162 may be formed of iron, iron powder, ferrite, or other
suitable core materials or material combinations. The windings 176,
178 may be formed of copper, aluminum, gold, silver, or other
suitable winding materials or material combinations.
[0062] Referring now to FIGS. 9 and 10, a side view of another
dual-mode filtering inductor 190 that incorporates a single
non-wound center leg 192 and a side schematic view of the magnetic
equivalent circuit thereof in accordance with another embodiment of
the present invention is shown. The dual-mode inductor 190
represents a special case of the dual-mode inductor 160 with zero
impedance along the paths P.sub.C and P.sub.D. It has a core 194
with a first core wound member 196, a second core wound member 198,
and lateral members 200. The impedance of the lateral members 200
may be divided and lumped together respectively with that of core
members 194 and 198. The non-wound center leg 192 has windows 203
and 205 on either side thereof. The first core wound member flux
.PHI..sub.A and associated reluctance R.sub.A, the second core
wound member flux .PHI..sub.B and associated reluctance R.sub.B,
and the center member flux .PHI..sub.E/F and associated reluctance
R.sub.E/F are shown in FIG. 10.
[0063] When the Y-component current I.sub.Y is equal to zero, then
the X-component flux .PHI..sub.X and the inductance L.sub.X are as
provided in equations 9 and 10 where the flux .PHI..sub.E/F is
equal to zero.
.PHI. X = NI X R A = .PHI. A = .PHI. B ( 9 ) L X = N .PHI. X I X =
N 2 R A ( 10 ) ##EQU00005##
On the other hand, when the X-component current I.sub.X is equal to
zero, the Y-component flux .PHI..sub.Y and the inductance L.sub.Y
are as provided in equations 11 and 12.
.PHI. Y = .PHI. ElF 2 = NI Y R A + 2 R C = .PHI. A = - .PHI. B ( 11
) L Y = N .PHI. Y I Y = N 2 R A + 2 R C .ltoreq. L X ( 12 )
##EQU00006##
The inductance L.sub.Y equal or smaller than the inductance
L.sub.X, and the core path P.sub.E/F is sized to accommodate the
Y-component.
[0064] In the following FIGS. 11-14, additional example
implementations of dual-mode filtering inductors are provided. The
X flux components and the Y flux components are shown in each of
FIGS. 11-14 for each of the associated dual-mode filtering
inductors. The X flux components are shown by the flow lines 206,
respectively. The Y flux components are shown by the flow lines
208, respectively.
[0065] Referring now to FIG. 11, a side view of another dual-mode
filtering inductor 210 that incorporates a continuous core 212 with
a split center leg 214 is shown in accordance with another
embodiment of the present invention. The core 212 has wound core
members 216, 218, lateral members 220, and a single window 221. The
center leg 214 is coupled between the lateral members 220 and has a
first center element 222 and a second center element 224. The
center leg 214 also has a break 226 with an associated gap G3
between the first center element 222 and the second center element
224. The gap G3 may be filled with materials to adjust the
effective permeability of the core or other characteristics
thereof.
[0066] Referring now to FIG. 12, a side view of another dual-mode
filtering inductor 230 that incorporates a core 232 within a
surrounded and floating center leg 234 is shown in accordance with
another embodiment of the present invention. The dual-mode inductor
230 also has a continuous core with wound core members 236, 238 and
lateral members 240. The floating center leg 234 is coupled
between, but is not attached to the lateral members 240, and is
within the window 241. A pair of gaps G4 and G5 exists between the
longitudinal ends 242 of the floating center leg 234 and the
lateral members 240. Although a pair of gaps are shown along the
center leg 234, any number of gaps may be incorporated. Also, gaps
may be included along the core 232. In addition, the gaps may be
filled with materials to adjust the effective permeability of the
core or other characteristics thereof.
[0067] Referring now to FIG. 13, a side view of another dual-mode
filtering inductor 250 that has an outer flux flow enabling shell
252 is shown in accordance with another embodiment of the present
invention. The dual-mode inductor 250 includes a continuous core
254 with wound core members 256, 258 and lateral members 260. The
shell 252 surrounds the core 254. A pair of small gaps G6 and G7
exist between the lateral members 260 and the shell 252 and a pair
of large gaps G8 and G9 exist between the wound core members 256,
258 and the shell 252. Instead of providing additional flux paths
via a center leg, the dual-mode inductor 250 provides additional
flux paths via the shell 252. Flux created by the passage of
current through the windings 270, 272 creates magnetic flux that
circulates through the wound core members 256, 258 and the shell
252, as shown. The Y flux components circulate over or across the
small gaps G6 and G7. Similarly, the shell 252 may formed or
consist of multiple sections with gaps therebetween. Again the gaps
may be filled with a variety of materials.
[0068] Referring now to FIG. 14, a side view of another dual-mode
filtering inductor 280 that has a core dividing center member 282
in accordance with another embodiment of the present invention is
shown. The dual-mode inductor 280 includes a non-continuous core
284 that has wound core members 286, 288 and lateral members 290
with breaks 292, 294. The center member 282 is isolated from or not
in contact with the lateral members 290, divides the window 291,
and is disposed within the gaps associated with the breaks 292,
294. The center member 282 extends between the lateral members 290
and is coupled between lateral elements 296 of each lateral member
290. Gaps G10, G11, G12, and G13 exist between each of the lateral
elements 296 and the center member 282.
[0069] The present invention provides a multiple dual-mode
filtering inductors and associated electronic circuits for diverse
applications. The stated inductors and circuits reduce the number
of inductors needed to provide both common-mode and
differential-mode filtering.
[0070] While the invention has been described in connection with
one or more embodiments, it is to be understood that the specific
mechanisms and techniques which have been described are merely
illustrative of the principles of the invention, numerous
modifications may be made to the methods and apparatus described
without departing from the spirit and scope of the invention as
defined by the appended claims.
* * * * *