Note: Descriptions are shown in the official language in which they were submitted.
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` BACKGR011ND OF T~IE INV~NTION
Field of the Invention
The present invention relates to an inductive component, upon whose
electrically conductive windings a tape consisting of high permeability
magnetic material is wound.
Description of the Prior Art
Conventional inductive components have a core of high magnetic
permeability, which may be tape wound or which can consist of layers of
plates, and which has electrical windings mounted upon said core. For ring-
shaped cores, the windings are typically wound over the core in the form of
toroid. Split tape-wound cores or cores of layers and perhaps glued plate
packets can be inserted into the finished windings.
Inductive components such as transformers, chokes, and transducers
are already known, in which the band-shaped core material consisting of high
permeability material is wound onto the prefabricated electrical windings.
Prior to the mounting upon the windings, the tape-shaped core material is
normally prewound to a similar diameter as it will later have on the winding.
It is subsequently heat-treated in order to remove mechanical stresses and
finally, perhaps after additional rewinding, wound upon the winding. The
completed wound core, which has the form of a ring-shaped core, encloses the
portion of the electric winding corresponding with the width of its tape wind-
ings, (see German Letters Patent 711,770; 722,211; 727,073; 729,918; 737,787;
and 915,588).
Although the degree of tape curvature must be kept to a minimum dur-
ing the winding, a decrease in the magnetic properties as had existed after
the heat-treatment cannot be avoided during the winding. In silicon-iron
alloys, the decrease can be held within tolerable limits, however, a consider-
able quality decrease must be acknowledged when utilizing the magnetically
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high duty nickel-iron alloys, (R. Bauer, "Transducer", Berlin/Gottingen/
Heidelberg, (Springer-Publishing House), 1953, Page 55, Paragraph 3).
SUM~RY OF THE INVENTION
It is an object of this lnvention to further improve an inductive
component onto whose electrically conductive winding, tape consisting of high
permeability material is wound. This is inventively obtained where the tape
of high permeability material consists of an amorphous a]loy.
As is known, amorphous metal alloys can be produced by having the
`~ molten alloy cooled so rapidly that solidification without crystallization
occurs. These amorphous alloys can be immediately obtained in the form of
thin tapes, whose thickness, for example, can be a few one-hundreths of a
; millimeter and whose width can be several millimeters. These amorphous alloys
can be distinguished from the crystalline alloys by utilizing x-ray defraction
analysis. In contrast to the crystalline materials which exhibit character-
istic sharp defraction lines, the amorphous metal alloys demonstrate an
intensity in the x-ray defraction picture which alters only slowly with the
defraction angle, which result is similar to that of liquids or common glass.
Depending upon the production requirements, the amorphous alloys can be com-
pletely amorphous or can comprise a two-phase mixture of the amorphous and
the crystalline state. The term "amorphous metal alloy", is to be generally
understood as an alloy which is at least 50%, or advantageously at least 80%,
amorphous.
Each amorphous metal alloy has a characteristic temperature, the
so-called crystallization temperature. If the amorphous alloy is heated to
or above said temperature~ it changes into the crystalline state. With heat-
~ treatments below the crystallization temperature, however, the amorphous
- state is retained.
The high permeability amorphous metal alloys presently known have
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the composition M Xl , wherein: M represents at least one of the metals
iron, cobalt, and nic~el; X represents at least one of the so-called glass-
forming elements boron, carbon, silicon, and phosphorous; and y lies between
approximately 0.60 and 0.95. In addition to the above-mentioned metals M,
the amorphous alloys can also contain additional metals, in particular
titanium, zircon, hafnium, vanadium, niobium, tantalum, chromium, molybdenum,
tungsten, manganese, palladium, platinum, copper, silver, or gold. In addi-
tion to the glass-forming elements X or, if necessary, even in place of them,
the elements aluminum, gallium, indium, germanium, tin, arsenic, antimony,
bismuth or beryllium can be present, (compare, for example, German OS
2,546,676; 2,553,003; 2,605,615; 2,628,362; and 2,708,151).
For high permeability amorphous alloys, it generally holds true
that with regard to their magnetic properties they are less sensitive to
deformations for example, those occurring upon the winding of the tape onto
an electrically conductive winding, than those tapes consisting of crystalline
high permeability alloys, with regard to their magnetic properties.
A number of cobalt-containing, amorphous alloys, specifically, as
they are disclosed in German OS 2,546,676 and 2,708,151, have a magneto-
striction which is close to zero. These alloys can advantageously have the
composition of CoaFebNicSidBePfCgAlh~ wherein
0.3 ~- a ~ 0.8,
0 ~ b C 0.1,
o C c ~ 0.4,
0 ~ d ~ 0.3,
0 ~ e C 0.3,
0 ~ f ~ 0.25,
0 C g C 0.15,
0 C h ~ 0.1,
and in addition,
a + b + c + d + e + f + g + h = 1,
0.6 ' a + b + c, and
; 0.1 ~ d + e + f -~ g + h.
The magnetic properties of these alloys are very insensitive to deformations.
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Tapes of such alloys can therefore be wound onto electrically conductive wind-
ings after a preceeding heat-treatment or, if necessary, completely without
such heat-treatment. Other high permeability, amorphous alloys, in particular
such of the composition Fe ~ibMe PdB sifc Alh, wherein Me represents one or
more of the metals cobalt, chromium, molybdenum, titanium, vanadium, copper,
and
; 0.1 ' a C 0.9,
~ O ~ b ~ 0.6,
- O ~ c ~ 0.4,
O C d ~ 0.25,
O C e C 0.3,
O ~ f C 0.3,
O c g ~ 0.15, and
O ~ h ~ 0.1;
and also
a + b + c + d + e + f + g + h = 1,
0.6 C a + b + c, and
0.1 ~ d + e + f + g + h,
have a perceptible magneto-striction. However, they respond to a relaxation
- annealing process at the relatively low temperatures of approximately 150
through 400C. The magnetic hysteresis losses for high frequencies, (for
example 20 kHz), are relatively low in these alloys after the heat-treatment.
Thus, when using such alloys, the component can be subjected to a heat-treat-
ment of between 150 and 400 C after the winding of the amorphous high
permeability tape onto the prefabricated, electrically conductive winding,
which has been provided with an insulation. Of course thi.s is true only as
long as the remaining materials used for the component are stable at these
temperatures.
It is particularly advantageous to design the electrically conductive
winding in a ring-shape and to wind the tape of the amorphous alloy in such a
toroidal shape that it largely surrounds or encases the electrically conductive
winding, preferably as much as possible. Particularly suited therefor are
amorphous tapes of not too wide a width, for example, of a width of 2 mm
through to 5 mm as they are readily produced directly from the melt. These
tapes can then be mounted onto the prefabricated, electrically conductive wind-
ing in one or several layers in a similar fashion to the one used in con-
ventional inductive components wound onto a prefabricated ring-shaped tape
core. Additionally, the structure has the advantage that the high permeability,
amorphous tape wound in toro-dal shape has a simultaneous magnetic screening
effect as a shell core.
The electrically conductive winding can advantageously be produced
of aluminum, whereby, in relation to copper, a considerable saving in weight
results. Moreover, the individual windings can readily be insulated from one
another in a manner unaffected by temperature changes, by means of an anodiz-
ing layer at their surface. For larger components, foils or films of a
synthetic material with the required temperature stability can also be
utilized for insulation.
If the weight savings is not a decisive factor, copper can naturally
be used for the electrically conductive winding. Insulation may then be
accomplished by the use of a lacquer or a glass fiber casing, which is
unaffected by temperature changes.
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The electrically conductive wlnding can be advantageously produced
out of a tape material, preferably an aluminum tape, which can be wound
similarly to the ring-shaped tape cores in a conventional component. With
such tape winding a particularly high space Eactor, and thus a particularly
compact design, can be obtained. The winding can also comprise several
partial windings electrically separated from one another, for example, the
primary and secondary winding of a transformer or transmittrr.
In order to obtain a high output with the smallest possible material
use, it is particularly advantageous to select an approximately square cross
section for the electrically conductive, ring-shaped winding which is to be
provided with a toroidal-shaped winding of high permeability tape. An
approximately rectangular cross section with a ratio of the side parallel to
the winding axis relative to the side at right angle to the winding axis of
approximately 2.5:1 through 1:1 is appropriate. It is also expedient to make
the winding packet of high permeability tape so thick that half the diameter
of the winding hole of the electrically conductive winding is filled by high
permeability material. Additionally, the space factors of the two windings
should be selected as great as possible if the smallest possible design volume
is to be obtained with a prescribed maximum output of the component. Indeed,
the maximum Otltput relative to volume unit increases with an increasing space
factor. For a winding consisting of aluminum tape, space factors through to
0.9 can be obtained, and in the high permeability toroidal-shaped winding,
space factors through 0.3 can be obtained. In order to simultaneously obtain
the highest possible maximum output relative to weight it is also advantageous
to select the ratio of exterior diameter relative to interior diameter of the
electrically conductive winding of approximately between 1.3 and 3.5, most
advantageously between 1.5 and 2.5.
In comparison to conventional components, more expensive high
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permeability material can therby ke saved in place of less expensive conductor
material. Indeed, under the previously stated criteria for the geometric design
of the component, the amount of high permeability material necessary for output
unit decreases with an increasing ratio between the exterior and the interior
diameter of the electrically conductive winding in the components, as the amount
of conductor material increases. In conventional camponents, e.g. in a ring-
shaped tape core provided with a toroidal-shaped electrically conductive winding,
this relationship is reversed.
In accordance with this invention, there is provided an inductive com-
ponent having an electrically conductive winding with a tape of high perme-
ability magnetic ma~erial wound on said electrically conductive winding, charac-
terized in that (a) the tape of high magnetic permeability consists of an amor-
phous alloy, and (b) the electrically conductive winding is a ring-shaped elec-
trically conductive winding having an appro~imately rectangular cross-section
with a ratio of the side parallel to the winding axis relative to the side at a
right angle to the winding axis, in the range of approximately 2.5:1 through l:l.
In accordance with another aspect of this invention, there is provided
a method for producing an inductive component ~hich comprises: forming a winding
of an electrically conductive material; insulating said electrically conductive
winding; forming a winding of high magnetically permeable material about the
electrically conductive winding; and heating the component thus formed to a
te~,perature of between 150 and 400 & in order to mechanically relax the magnet-
ically permeable material.
The invention is to be more precisely explained with the aid of several
Figures and examples. Various other objects, advantages, and features of the
present invention will became
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readily apparent from the ensuing detailed description and the
novel features will be particularly pointed out in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
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Figure 1 is a perspective view of a preferred embodiment.
Figure 2 is a schematic sectional view taken along line
II-II in Figure 1.
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Figure 3 which is located on the second page of drawings is a graph
showing the relationship between the ratio of mass relative to output and the
ratio of the exterior diameter relative to the interior diameter, for a com-
ponent according to Figures 1 and 2, with comparison curves for a conventional
component addecl.
Figure 4 is a graph similar to Figure 3 but showing in addition the
relationship between the ratio of volume to output and the ratio of exterior
diameter relative to the interior diameter, for a component according to
Figures 1 and 2, with comparison curves for a conventional component added.
Figure 5 is a view similar to Figure 2 showing an alternate embodi-
ment of this invention.
DESCRIPTIO~ OF THE PREFERRED EMBODIMENTS
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A transformer according to this invention is more precisely explain-
ed with the aid of Figures 1 and 2 in the following sample embodiment. The
ring-shaped electrically conductive winding of this transformer is subdivided
into two partial windings, a primary and a secondary winding and has a square
cross section and is toroidally surrounded by a winding of high permeability,
amorphous tape.
The transformer is designed for a primary voltage of 300 V, a
secondary voltage of 48 V and a transmittable output of 670 W at a frequency
of 20 kH~. The ambient tempPrature is to be 60C, the permissible overtemper-
ature is 60 K The magnetic losses of the high permeability winding amount
to 28 W/kg.
Proceeding Lrom the operating conditions, the following geometric
data were determined for the transformer: ,
Interior diameter of the transformer d = 1.4 cm
Exterior diameter of the transformer d = 7.9 cm
Height of the transformer h = 3.4 cm
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Interior diameter of the electricallydl= 2.8 cm
conductive winding
Exterior diameter of the electricallyd2= 6.8 cm
conductive winding
Height of the electrically conductive winding h2= 2.0 cm
Magnetic iron cross section 0.9 cm2
Effective conductor cross section 3.4 cm
Average iron path length 15.1 cm
Average electric winding length 9.8 cm.
The transformer was constrùcted with a primary winding 1 having
122 windings of 0.08 mm thick and 18 mm wide aluminum tape and a secondary
winding 2 with 20 windings of 0.45 mm thick and 18 mm wide aluminum tape. A
` 19 mm wide and 0.2 mm thick polyimide film was placed between the windings as
insulation which, for the sake of clarity, was not separately illustrated in
Figure 2. The space factor of the winding consisting of the two partial
windings 1 and 2 and having a square cross section is approximately 0.85. The
ratio of exterior diameter d2 relative to interior diameter dl of the winding
is 2.4.
A polyimide film 3 is again used as cover insulation of the
electrically conductive windings 1, 2 said film may be applied on the winding
by the use of heat shrinkable plastic.
Around the winding 1, 2 thus insulated, 900 windings 4 consisting
of 2 mm wide and 0.05 mm thick tape of high permeability, amorphous alloy
FeO 40Nio 40P0 14Bo 06 were then wound around in such a manner that they
surrounded the electrically conductive winding 1, 2 in a toroidal shape.
Only the point at which the electric connections 5 are guided out of primary
winding 1 and secondary winding 2, is not covered by the high permeability
winding. The free end of the amorphous tape can simply be pushed underneath
an adjacent winding in order to maintain the high permeability winding in
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place. The high permeability winding, whose space factor i9 approximately
O.Z, fills approximately one-half of the diameter dl, (which is the winding
hole of the electrically conductive winding).
To achieve mechanical relaxation and to improve the dynamic proper-
ties, particularly to decrease the magnetic losses of the high permeability
winding, the completely wound transformer was annealed in air at a temperature
of between approximately 300 and 350C for one hour. It was subsequently
cooled, in a controlled fashion, with a cooling speed of approximately 100
through 250C per hour, and was then allowed to cool further below 200C in an
uncontrolled manner. A thin oxide layer sufficient for the insulation of
the individual windings relative to one another is also formed during this
annealing process on the tape consisting of the amorphous alloy, which reduces
the eddy current probl~m. Additionally, a synthetic material film can be
applied onto the high permeability winding after the annealing process as an
additional protection.
For the transformer described, the aluminum has a weight of 138 g
and the tape of the amorphous alloy has a weight of 69 g, Accordingly, the
weight of the magnetic material is much lower than that of the conductor
material~
From Figure 3 it is apparent that with an increasing ratio of the
exterior relative to the interior diameter of the electrically conductive
winding in the components, according to the invention, the more expensive high
permeability material can be reduced because of the increased amount of
cheaper conductor material.
The ratio of mass or weight m to output P in g/W are plotted in
Figure 3 on the ordinate and the ratio of exterior diameter d2 to interior
diameter dl is plotted on the abscissa. The plotted curves 11, 12, 13 are
valid for the inventive components. For this graph, the electrically conduc-
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tive winding consists of aluminum and has a square cross section and a space
factor of 0.85 and the high permeability winding of amorphous material is
designed in a toroid-shaped, has a space factor of 0.2, and fills one-half
of the diameter dl of the winding hole of the electrically conductive winding.
For the magnetic material iron losses of 28 W/kg are assumed, at an induction
of 0.2 T and a frequency of 20 kH~. The operating temperature is 60C with
an overtemperature of 60 K .
Curve 11 illustrates the mass of the high permeability material,
curve 12 illustrates the mass of the electrically conductive material and
curve 13 illustrates the total mass in reference to the output respectively.
As can be readily seen in a comparison of curves 11 and 12, the mass of the
-~ necessary magnetic material is smaller with diameter ratios d2/dl above
approximately 1.9 than the mass of the required conductor material relative
to the output obtained.
Curves 14, 15 and 16 are comparison curves, shown in broken line,
relating to conventional components. It is thereby assumed, that the high
permeability winding is a ring-shaped tape core corresponding to the electric-
ally conductive winding of the inventive components with regard to the geo-
metric shape and the space factor. Additionally, the electrically conductive
winding consists of copper wire and corresponds in geometric shape and space
factor to the high permeability winding of the inventive component. Curve 14
illustrates the mass of the high permeability material, curve 15 shows the
mass of the conductor material, and curve 16 shows the total mass relative to
the cutput respectively in dependency upon the ratio of the exterior diameter
d2 relative to the interior dl of the ring-shaped tape core. A'comparison of
curves 14 and 15 shows that in conventional components the mass of the
magnetic material relative to the output increases while the mass of the con-
ductor material relative to the output decreases. Moreover, a comparison
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of curves 13 and 16 shows that with a given diameter ratio, the mass per out-
put is considerably greater in conventional components than in the inventive
components.
Curves 13 and 16 are once more shown in Figure 4. ~dditionally,
Figure 4 contains two other curves oE which curve 17 represents the volume V
of the inventive component and curve 18 represents the volume V oE the con-
ventional component relative to output P respectively versus the diameter
ratio d2/dl. The assumed properties of the components are the same as in
Figure 3. Curve 17 and 18 show that with a given diameter ratio the volume
per output is somewhat larger in the inventive components than in conventional
components. However, in relationship to the considerable saving possibilities
of high permeability material, as is apparent from Figure 3 because of greater
use of the cheaper conductor material in the inventive components, this is not
of great importance~ From Figure 4 it is also obvious that with diameter
ratios between approximately 1.4 and above 3 through approximately 3.5, the
mass as well as the volume relative to the output are particularly low in the
inventive components. Particularly advantageous diameter ratios exist between
approximately 1.5 and 2.5, and in addition, with an increasing diameter ratio,
the previously mentioned advantage of saving high permeability material also
exists.
Thus far, only components have been described in the sample embodi-
ments wherein the electrically conductive windings exhibit the particularly
advantageous square cross section. However, the invent;on is not limited
thereto, the electrically conductive windings can also have other cross
sectional forms. For example, the cross section can also be rectangular.
However, as has been previously mentioned, the ratio between the side parallel
to the winding axis and the side at right angle relative to the winding axis
should lie between 2.5:1 and 1:1.
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Furthermore, particularly with components having several electric-
ally conductive windings, the electrically conductive winding can consist of
parts of different heights. One sample embodiment therefore is schematically
illustrated in Figure 5. The electrically winding consists of a primary wind-
ing 21 and two secondary windings 22 and 23 which, for example, consist of an
aluminum tape whose height decreases from the exterior towards the interior.
Due to decreasing the height of the individual partial windings towards the
interior, more room is left for the winding 24 consisting of a tape of a high
permeability, amorphous alloy in the winding hole so that the outlines of the
cross section of the high permeability winding 24 more closely approximate
a rounded-off rectangle than in the component according to Figure 3.
While we have disclosed an exemplary structure to illustrate the
: principles of the invention, it should be understood that we wish to embody
,
within the scope of the patent warranted hereon all such modifications as
reason~bly ~nd properly come withln the scope oi o~r contri~utlon to the ~rt.
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