U.S. patent number 3,803,479 [Application Number 05/289,767] was granted by the patent office on 1974-04-09 for voltage regulating transformer.
This patent grant is currently assigned to Foster Transformer Company. Invention is credited to Ramesh P. Rathor.
United States Patent |
3,803,479 |
Rathor |
April 9, 1974 |
VOLTAGE REGULATING TRANSFORMER
Abstract
A voltage regulating transformer for providing a constant output
is disclosed. The transformer has a coil connected in series with a
capacitor to form a resonant circuit. The transformer is formed of
a plurality of laminate members, the members forming a core about
which the coil is wound. The other legs of the laminate members
form a yoke about the coil. Alternate laminate members are formed
with a magnetic gap to provide a plurality of magnetic gaps in the
flux path of the coil.
Inventors: |
Rathor; Ramesh P. (Cincinnati,
OH) |
Assignee: |
Foster Transformer Company
(Cincinnati, OH)
|
Family
ID: |
23112993 |
Appl.
No.: |
05/289,767 |
Filed: |
September 18, 1972 |
Current U.S.
Class: |
323/308; 336/212;
336/178; 336/234 |
Current CPC
Class: |
G05F
3/06 (20130101) |
Current International
Class: |
G05F
3/04 (20060101); G05F 3/06 (20060101); G05f
001/38 (); G05f 007/00 () |
Field of
Search: |
;323/6,4S,60,61,44,57
;336/178,212,234 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goldberg; Gerald
Attorney, Agent or Firm: Schenk; John G.
Claims
1. A voltage regulating transformer having magnetic conductivity,
comprising a plurality of stacked, interspersed first and second
laminate members each having an E-I configuration and together
defining a composite, laminated transformer core and yoke, said
first laminate members defining a continuous flux path and said
second laminate members having a gap in the flux path thereof, thus
defining a plurality of laterally spaced magnetic gaps in the flux
path of the transformer core, said laminate members defining a coil
supporting portion, coil means wound about said coil supporting
portion, means connecting said coil means to an input source of
alternating current, means connecting said coil means with output
terminals, said plurality of spaced magnetic gaps in the flux path
of said transformer core providing spaced regions of high
reluctance whereby the transformer becomes saturated quickly
thereby providing a
2. A voltage regulating transformer as in claim 1, wherein each
laminate member comprises a pair of spaced, substantially parallel
end elements, said coil supporting portion extending from one end
element toward the other end element substantially intermediate the
ends thereof, and a pair of leg elements on either side of and
parallel to the coil supporting portion and extending between the
end elements adjacent the opposite ends of the end elements, said
coil wound around the coil supporting portion
3. A voltage regulating transformer as in claim 2, wherein the coil
supporting portion on each of said second laminate members is
shorter than the leg elements and is spaced from said other end
element to define said
4. A voltage regulating transformer as in claim 2, wherein the leg
elements on each of said second laminate members are shorter than
the coil supporting portion thereof and said leg elements are
spaced from the other end element to define a pair of magnetic gaps
in the flux path thereof.
5. A voltage regulating transformer as in claim 1, wherein a
capacitor is connected in series with said core between the core
and the input source
6. A voltage regulating transformer as in claim 1, wherein said
laminate members each comprise an E-element and an I-element, said
E- and I-elements engaging one another to form the magnetic circuit
of the
7. A voltage regulating transformer as in claim 6, wherein each
E-element includes an end element and three leg elements extending
laterally therefrom, the middle leg element comprising said coil
supporting portion
8. A voltage regulating transformer as in claim 6, wherein each
E-element includes an end element and three leg elements extending
laterally therefrom, the middle leg element comprising said coil
supporting portion, the leg elements on either side of the coil
supporting portion spaced from
9. A voltage regulating transformer as in claim 6, wherein the
first and second laminate members are stacked in alternating
relationship with alternate laminate members reversed so that the
I-element of a first laminate member is adjacent an end element of
a second laminate member.
10. The voltage regulating transformer according to claim 1 in
which said first and second laminate members are alternately
stacked to form said
11. A voltage regulating transformer having magnetic conductivity
comprising in combination a plurality of first laminate members
each defining a continuous flux path, a plurality of second
laminate members interspersed among said first laminate members and
each having a magnetic gap in the flux path thereof, said first and
second laminate members being stacked together to form a composite
laminated transformer core having a plurality of laterally spaced
magnetic gaps in the flux path of said stacked laminate transformer
core wherein the magnetic gaps provide regions of high reluctance
whereby the transformer becomes quickly saturated to provide a
constant output over a wide range of input fluctuation, each of
said laminate members including a pair of spaced, substantially
parallel end elements, a pair of leg elements and a coil supporting
portion extending between said end elements, coil means wound about
said coil supporting portion, means connecting said coil means to
an input source of alternating current including a capacitor
connected in series with the coil and with the source to form a
series resonant
12. A voltage regulating transformer as in claim 11, wherein said
laminate members each comprises an E-element and an I-element, each
said E-element including one end element and three leg elements
extending laterally therefrom, said coil supporting portion
comprising the middle of said leg elements, said other end element
comprising the I-element, said E- and I-elements engaging one
another to form the magnetic circuit of the transformer, and said
coil supporting portion on said second laminate members being
shorter than the leg elements on either side thereof and
13. A voltage regulating transformer as in claim 11, wherein said
laminate members each comprises an E-element and an I-element, each
of said E-elements including one end element and three leg elements
extending laterally therefrom, said coil supporting portion
comprising the middle of said leg elements, said other end element
comprising the I-element, said E- and I-elements engaging one
another to form the magnetic circuit of the transformer, said leg
elements on either side of the coil supporting portion of the
second laminate members being shorter than the coil supporting
portion and spaced from the I-element to define a pair of
14. The voltage regulating transformer according to claim 11 in
which said first and second laminate members are alternately
stacked to form said composite transformer core.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to transformers and more
particularly to a voltage regulating transformer to provide a
constant voltage output.
Numerous voltage regulating devices are known in the art. U. S.
Pat. No. 3,585,493 issued to Herbert Moerlein is an example of
prior voltage regulating transformers. An unusual feature of these
type transformers is the magnetic gap, either an air gap or
nonmagnetic material, extending the entire depth of the
transformer. The core members are made of a ferromagnetic material
and come in solid bar shapes. This construction limits the
usefulness of such transformers in that given sizes only are
obtainable. Generally, these transformers are of a somewhat large
and bulky size necessitated by the solid type construction.
Accordingly, it is an object of this invention to provide a voltage
regulating transformer having great utility.
A further object of this invention is to provide a voltage
regulating transformer having a plurality of magnetic gaps to
provide saturation and stabilization of the transformer at a lower
voltage.
A still further object of this invention is to provide a voltage
regulating transformer of simple and economical construction and
which uses a plurality of laminate members to provide the yoke and
core elements.
Yet another object of this invention is to provide a voltage
regulating transformer which can be made of a reduced size yet
provides a constant output voltage over a wide range input voltage
fluctuation.
And a still further object of the present invention is to provide a
voltage regulating transformer which is simple to construct and may
be constructed less expensively than voltage regulating devices
presently available.
SUMMARY OF THE INVENTION
This invention provides an improved voltage regulating transformer
for providing a stable output voltage over the wide range of input
voltage fluctuation. The transformer is formed with a plurality of
laminate members which form the core and yoke portions of the
transformer. Alternate laminate members have a magnetic gap therein
so as to provide a plurality of magnetic gaps in the flux path of
the coil. A capacitor is connected in series with the primary coil
to form a resonant circuit. The plurality of magnetic gaps permit
early saturation of the transformer so as to stabilize the
transformer output.
Other objects, details, uses and advantages of this invention will
become apparent as the following description of the exemplary
embodiments thereof presented in the accompanying drawings
proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show present exemplary embodiments of
this invention in which:
FIG. 1 is a perspective view, partially exploded, illustrating one
exemplary embodiment of this invention showing the laminate
structure of the transformer;
FIG. 2 is a schematic electrical circuit diagram of the voltage
regulating transformer of FIG. 1;
FIG. 3 is a view of the voltage regulating transformer, partly
schematic, illustrating the transformer of FIG. 1 in longitudinal
section;
FIG. 4 is a view of one laminate member forming a part of the
transformer of FIG. 1;
FIG. 5 is a view of the laminate members having a magnetic gap used
in combination with the laminate members of FIG. 4 to construct the
transformer of FIG. 1;
FIG. 6 is a graph illustrating the saturability of the transformer
of this invention;
FIG. 7 is a view taken along line 7--7 of FIG. 3; and
FIG. 8 is a view similar to FIG. 5 illustrating a laminate member
to provide different magnetic gaps.
DESCRIPTION OF ILLUSTRATED EMBODIMENTS
Reference is now made to FIGS. 1 and 3 of the drawings which
illustrate one exemplary embodiment of the improved voltage
regulating transformer of this invention, which is designated
generally by the reference numeral 10. The transformer 10 is
provided with a primary coil 12 wound about a coil supporting
portion, shown generally as 14, of the transformer core 15. A
secondary coil 16 is wound about the primary coil 12. The ends of
the primary coil 12 are connected to a pair of input terminals 18
and 20, the latter being connected through a capacitor 22. The ends
of the secondary coil 16 are connected to the output terminals 24
and 26. Although the embodiment herein described is shown to have a
primary coil and a secondary coil, it is obvious that a single coil
may also be utilized.
The structure of the transformer core 15 can best be seen by
referring to FIGS. 1, 4, 5 and 7. The core 15 is formed of a
plurality of first laminate members defining a continuous flux
path, and a plurality of second laminate members each having a
magnetic gap therein and interposed among the first laminate
members to define a composite stacked laminate core having a
plurality of laterally spaced magnetic gaps in the flux path
thereof. Each laminate member is formed of an "E" and "I" element
28 and 30, respectively. Referring in particular to FIG. 4, the
laminate member comprises a pair of end elements 30 and 38, with a
pair of leg members 32 and 36 and a coil supporting portion 34.
More specifically, the E-element has three legs 32, 34 and 36
outwardly extending from an end element 38 into engagement with the
I-element or end element 30.
The laminate member shown in FIG. 5 has the same construction as
that of FIG. 4 and, accordingly, corresponding structure will be
provided with the same numerical designation and not described
again. The difference between the laminate members of FIGS. 4 and 5
is that the center leg 40 does not extend outwardly the same
distance as the legs 32 and 36. Thus, when the E-element member of
FIG. 5 is placed in abutting relationship with the I-element or end
element 30, a gap 42 exists between the end of the leg 40 and the
I-element 30.
The laminate members are formed from any suitable magnetic material
so as to provide a low-reluctance flux path for the flux generated
by the coils 12 and 16. The laminate members are stacked in opposed
relationship one to the other. In other words, the leg portions
extend in opposite directions and the element 38 of one laminate
member is aligned with the I-element 30 of the next laminate
member. The laminate members are held together by any suitable
means, such as nonmagnetic rivets or the like 43 (FIG. 3),
extending through apertures 44, 46, 48 and 50 of the E- and
I-elements.
Referring in particular to FIG. 7, it is seen that the coil
supporting portion, comprised of adjoining legs of 34 and 40, is
provided with a plurality of magnetic gaps. The number of magnetic
gaps, which in this instance is an air gap, is dependent on the
number of laminate members utilized in forming the core 15.
The transformer 10 is intended for service with an alternating
current source applied to input terminals 18, 20. The capacitor 22
and primary coil 12 are selected to form a series tuned inductive
capacitive circuit as shown in FIG. 2. The output terminals 24 and
26 are magnetically coupled through the secondary coil 16 to the
primary coil 12. The effect of a loose coupling between the output
and input terminals is described in the aforementioned Moerlein
patent. It is sufficient herein to say that a low reluctance flux
path is provided in the laminate member shown in FIG. 4 and a
region of high reluctance is provided by the laminate member shown
in FIG. 5. It has been found that a transformer having the laminate
members of this invention providing alternating magnetic gaps
(regions of high reluctance) will become saturated at a lower
voltage than other transformer core structures. Such a transformer
will thus provide a stable output from the secondary coil which is
relatively insensitive to fluctuations in the input voltage over a
wide range.
Referring in particular to FIG. 6, line 52 represents the capacitor
voltage. The curved line 54 represents the voltage in a standard
transformer not of this invention and the curved line 56 represents
the voltage across the primary coil of a transformer made in
accordance with the present invention. The Y axis represents output
voltage and the X axis represents input voltage. It is seen that
curved line 54 flattens out at approximately 110 volts input. The
flattened out portion would represent a standard transformer having
reached a saturation point. Due to the alternating magnetic gaps of
high reluctance regions, the transformer 10 of the present
invention becomes saturated at a much lower voltage. The
transformer reaches the saturation point at approximately 96 volts
and the curved line 56 flattens out at this point. At the
transformer saturation point, the curve 56 will flatten out along
the region designated generally as 57. This part of the curve,
i.e., region 57, is the region which controls the flux change in
the secondary coil. Hence, should the input voltage increase to 120
volts, the output of the secondary coil would not change due to the
saturation of the transformer. It has been found that the regulated
output voltage of the transformer of this invention will not vary
more than 1 to 2 percent over the wide range of variation in input
voltage. It should be noted, however, the output voltage may be
changed by varying the capacitor and coil.
FIG. 8 represents a modification of the laminate member 28
corresponding to the laminate member shown in FIG. 5. The identical
elements of the laminate member 28 of FIG. 8 bear the same
reference numerals as used in describing the laminate members of
FIGS. 4 and 5. In FIG. 8, the E-element has been modified such that
the center leg 54 extends outwardly from the end element 38 a
distance sufficient to engage the I-element 30 (leg 54 is equal to
leg 34 of FIG. 4). Legs 52 and 56, extending outwardly from end
element 38, terminate at a distance short of the I-element 30 so as
to provide magnetic gaps 58 and 60. Thus, when the laminate member
of FIG. 8 is combined with the laminate member of FIG. 4, a
plurality of magnetic gaps is formed in the resulting structure.
The resulting transformer in this embodiment provides a constant
voltage output as hereinabove described.
While the above described magnetic gaps have been discussed and
illustrated as airgaps, it should be noted that nonmagnetic
material may be utilized to provide the necessary magnetic gap. It
can be seen that a transformer constructed in accordance with this
invention will become saturated at a low voltage due to the
multiplicity of magnetic gaps formed therein. The output voltage
will be regulated within approximately 1 to 2 percent over the wide
range of the input voltage. Accordingly, the objectives
hereinbefore set forth have been accomplished.
While present exemplary embodiments of this invention have been
illustrated and described, it will be recognized that this
invention may be otherwise variously embodied and practiced by
those skilled in the art.
* * * * *