Note: Descriptions are shown in the official language in which they were submitted.
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TRANSFORMER
Field of the Invention
The invention relates to the field of electrical engineering and concerns
the basic electrical engineering equipment of electric power stations,
substations, power lines, in radio engineering, in devices for measuring,
automatic control and regulation.
Background Art
Transformers are electromagnetic static converters of electrical energy
which have two or more inductively coupled windings and are designed for the
conversion of an alternating (sinusoidal) current of one voltage into an
alternating current of another voltage with the same frequency.
The principle of operation of a transformer is based on the effect of
electromagnetic induction found by M. Faraday in 1831 (B.N. Sergeenko,
V.M. Kiselev, N.A. Akimova. Electrical Machines. Transformers. Pub.
"Vysshaya Shkola," Moscow, 1989, 350 pages). In accordance with specific
features of construction and use, transformers can be divided into power,
welding, measuring and special transformers.
Power transformers, which are a necessary element of an industrial
power network, have attained the most widespread use.
Transformers have two basic parts: a magnetic circuit and windings.
Furthermore, high-power transformers have a cooling system.
The magnetic circuit is the structural base for mounting and fixing
windings, taps and other elements of a transformer, and serve for
amplification
of the magnetic coupling between the windings.
The part of the magnetic circuit on which the windings are arranged is
called the core, the remaining part, closing the magnetic circuit, is called
the
yoke. The windings of a transformer serve to create a magnetic field by means
of which electrical power is delivered. The winding of the transformer to
which electrical power is applied is called the primary winding, while the
winding from which power is taken is called the secondary winding.
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Known inventions are concerned with the creation of special
transformers or with changes of particular structural elements of the
transformer: realization of magnetic circuits from certain materials and their
structural appearance, connection of magnetic circuits to each other where
there is an n number of magnetic circuits, use of different types of
insulation
and cooling systems, realization of the' windings, additional elements in
order
to enhance noise immunity.
A transformer is known for vehicles [PCT (WO), 93/14508j. The small
size light transformer comprises a shell-type iron core on which inductively
coupled input and output windings are wound. A magnetic element with an air
gap is provided between the input and output windings, while a magnetic
element creating strong magnetic coupling is located between the output
windings. The element is disposed in a gap Sd surrounded by the core and
consists of a magnetic circuit without gaps and an insulating plate holding
the
1 S magnetic circuit and insulating it from the core and windings.
A transformer is known [PCT (WO), 93/16479, in which the core is
made from ferromagnetic wire. A spirally wound core from ferromagnetic wire
is proposed. The core is used in a differential current sensor in a switch to
open a circuit, which operates when there is a short circuit to ground. The
ferromagnetic wire is wound in a spiral, the turns of which are parallel to
each
other and extend over the whole length of the core. The latter is positioned
near current lines, with monitoring of a short circuit therein, wherein both
lines are connected to a power source. The currents in them flow in opposite
directions. The core interacts with a magnetic field created by those
currents.
Where a ferromagnetic wire is used, it is possible to. substantially increase
the
surface area of the core without increasing its cross section, and
consequently,
size.
A transformer is known [RU, C1, 2041514 consisting of one or several
strip cores made from a magnetic alloy comprising silicon, boron, iron and
several windings inductively coupled to the core, wherein the magnetic alloy
additionally comprises copper and one or several components selected from the
group consisting of niobium, tantalum, tungsten, molybdenum, chromium, and
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vanadium, with the following ratio of alloy components, atom percent: copper
- 0.5-2.0; one or several components from the group consisting of niobium,
tantalum, tungsten, molybdenum, chromium, vanadium - 2-5; silicon - S-18;
boron - 4-12; iron - balance.
A transformer is known [PCT (WO}, 93/18529] comprising 3 or 4 types
of insulation units with one winding. Transformers of this type are easily
assembled with small expenditure of time.
A current transformer with strip insulation is known [RU, C1, 2046425]
comprising a single-turn or multitum primary winding and secondary windings
which are placed in a damping screen and have terminals. Wherein the
aforesaid windings are secured by means of insertion support and connecting
bushings and are covered with epoxy compounds. The transformer is
additionally provided with insulation bushings, a screen which is placed on
the
primary winding, and support clamps. Insulation bushings are mounted in
semi-oval slots of the clamps, the damping screen is made open and consists of
two parts, with an insulating pad mounted in the gap between the two parts,
and the insertion support bushings are mounted on the insulating bushings in a
manner adaptable for securing the damping screen.
A high-voltage transformer is known [RU, C1, 2035776] comprising a
porcelain housing mounted on a socket on which an active portion enclosed in
the housing is positioned on compressing posts. The active portion consists of
a mixed rectangular magnetic circuit with yokes, upper and lower horizontal
cores on which windings are positioned. In order to reduce the noise
immunity the transformer is provided with additional screens - a middle one,
upper and lower ones, and a capacitive screen.
A winding for a high-voltage transformer is known [PCT (WO},
93/18528]. A connecting element is secured to the conductive portion of the
winding to enhance its mechanical properties, and a second connecting
element is connected to the aforesaid connecting element by means of
insulating elements. Such a winding can be used as a low-voltage winding with
a small number of turns in dry transformers with a resin poured over them.
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A heavy-current transformer is known [RU, Cl, 2027238] comprising a
primary winding disposed on a toroidal core and a secondary winding
encompassing the primary winding. Wherein the secondary winding is made
by a bundle of flexible conductors placed in the inner cavity of the torus in
N
sections, and from the outer side of the torus in N-1 sections, where N is the
number of turns of the secondary winding, wherein the bundle is arranged in
one or more layers on the outer side of the torus.
However, all the known transformers are built according to one
principle, in particular - supplying electrical power to the primary winding
and
taking electrical power from the secondary winding, and they all have these
drawbacks:
- multiturn secondary windings in step-up transformers, which
nevertheless operate in a rather narrow frequency range (50-400 Hz); the
limited frequency range of the transformers being related to losses in the
magnetic circuit at higher frequencies;
- high resistance of the windings, i.e. the necessity that the no-load
condition of the transformer be taken into account during calculations of the
number of turns in the secondary winding to obtain a predetermined output
voltage;
- the complexity of the construction of the transformers when all
possible kinds of additional elements, insulation etc. are used to reduce the
aforesaid drawbacks.
Disclosure of the Invention
At the base of the invention lies the object of creating such a transformer
in which the possibility of winding the secondary winding with wire, including
wire with a cross-section equal to the cross-section of the primary winding,
is
realized, reduction of the number of turns in the secondary winding of high-
voltage transformers and expansion of the number of variants of existing
transformers are attained.
This object is achieved in that a construction of a transformer is
proposed which comprises a magnetic circuit, at least two windings, inlets for
a
power supply, outlets for a load, wherein the primary winding consists of two
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sections with an identical number of turns, the sections being connected to
each other in a series circuit.
A transformer is proposed in which two sections of a primary winding
are wound in one direction on one core of the magnetic circuit, the sections
5 are connected in a series circuit by connection of the outs of the windings,
and
the point of their connection serves as an outlet for the load, while the ins
of
the windings of the sections serve as inlets for the power supply.
The aforesaid technical result is achieved by creating a transformer, two
sections of the primary winding of which are wound in one direction on one
core of the magnetic circuit, the outs of the windings of the sections are
connected in a series circuit, while the ins of the section windings serve as
inlets for the power supply.
The secondary winding is wound on the same core of the magnetic
circuit, over the sections of the primary winding.
The aforesaid technical result is achieved by creating a transformer, two
sections of the primary winding of which are wound in opposing directions on
one core of the magnetic circuit, the out of the winding of the first section
and
the in of the winding of the second section are connected to each other in a
series circuit, while the in of the winding of the first section and the out
of the
winding of the second section serve as inlets for the power supply.
The secondary winding is wound on the same core of the magnetic
circuit over the sections of the primary winding.
The indicated object is achieved by creating a transformer in which both
sections of the primary winding are wound in one direction on two cores of
one magnetic circuit, the out of the winding of the first section and the in
of
the winding of the second section are connected to each other in a series
circuit, while the in of the winding of the first section and the out of the
winding of the second section serve as inlets for the power supply. The
secondary winding is wound on both sections of the primary winding,
encompassing both cores of the magnetic circuit.
The same technical result is achieved by creating a transformer in which
both sections of the primary winding are wound in opposing directions on two
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cores of one magnetic circuit, the outs of the windings of the sections are
connected to each other in a series circuit, while the ins of the windings of
the
sections serve as inlets for the power supply.
The secondary winding is wound on both sections of the primary
winding, encompassing both cores of the magnetic circuit.
The same technical result is achieved when both sections of the primary
winding are wound in one direction on two cores of one magnetic circuit,
wherein the in of the winding of the first section is connected to the out of
the
winding of the second section, the out of the winding of the first section is
connected to the in of the winding of the second section, the points of their
connection serve as inlets for the power supply.
The secondary winding is wound on both sections of the primary
winding, encompassing both cores of the magnetic circuit.
The indicated object is achieved by creating a transformer in which two
sections of the primary winding are wound in opposing directions on two cores
of one magnetic circuit, both sections are connected to each other by
connection of the ins and outs thereof respectively, and the points of their
connection serve as inlets for the power supply.
The secondary winding is wound on both sections of the primary
winding, encompassing both cores of the magnetic circuit.
The following lies at the base of the invention: sections of the primary
winding are wound and connected to each other in such a manner that the
magnetic flux created by one of such sections during operation of the
transformer compensates the magnetic flux created by the other section of the
primary winding.
If the two sections of the primary winding of the proposed transformer
are connected to an alternating current network having a voltage U~, then a
current i~ will flow therealong. The magnetomotive force of one section of the
winding i~w~ due to the current i~ creates an alternating magnetic flux F~ in
the magnetic circuit of the transformer. Similarly, a magnetomotive force
i~w2,
which is equal to the mmf of the first section i~w~, appears in the second
section of the winding. Since the sections are connected to each other in a
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series circuit, the alternating magnetic flux F2 appearing in the second
section
of the primary winding and directed counter to the magnetic flux F1 will
compensate the magnetic flux of the first section F~. However, due to the
induction of the mmf the permeability of the magnetic circuit changes. When
the network current drops during half cycles, restoration of the permeability
occurs in the magnetic circuit, and consequently, an electromotive force (emf)
is induced in the primary and secondary windings. Wherein, during a half
cycle of current in the primary winding, the voltage in the secondary winding
passes through a whole period.
In the case where both windings are wound in opposing directions with
an identical number of toms, but are connected to each other in a series
circuit
by opposing leads (the out of the winding of the first section and the in of
the
winding of the second section), the magnetic flux in the primary winding io
will also be equal to zero, i.e. the same technical result can be attained as
in
the case where the windings of both sections are wound in one direction.
When RH is connected to the secondary winding, the form of the voltage does
not change. The output voltage depends on an increase of the number of turns
in the secondary winding as compared with the number of turns in the primary
winding.
Such a realization of the proposed transformer results in:
1 ) a reduction in the number of turns in the secondary winding by 10-20
times, and consequently, the dimensions of the transformer are reduced;
2) the possibility of winding the secondary winding with a thick wire
having a cross section equal to the cross section of the wire in the primary
winding;
3) the secondary winding having a number of toms either greater or less
than the number of turns in the primary winding, depending on the necessity
of a high voltage at the output of the transformer.
Brief Description of the Drawings
- Further the invention will be explained by a description of concrete
examples of its embodiment and the accompanying drawings in which:
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8
Fig. 1 shows the device being patented - a transformer in accordance
with the invention (circuit);
Fig. 2 shows another embodiment of the transformer in accordance with
the invention (circuit);
Fig. 3 shows one of the embodiments of the transformer in accordance
with the invention (circuit};
Fig. 4 shows one more embodiment of the transformer in accordance
with the invention (circuit);
Fig. 5 shows one more embodiment of the transformer in accordance
with the invention (circuit);
Fig. 6 shows one of the embodiments of the transformer in accordance
with the invention (circuit);
Fig. 7 shows one of the embodiments of the transformer in accordance
with the invention (circuit);
Fig. 8 shows a stylized dependence of the increase of current and voltage
in the primary and secondary windings of a transformer with a ferrite magnetic
circuit;
Fig. 9 shows a stylized dependence of the increase of current and voltage
in primary and secondary windings of sheet steel.
Best Variants of Carrying Out the Invention
A comprehensive description of embodiments of the transformer being
patented in accordance with the invention is given below.
A transformer in accordance with the invention (according to the
embodiment shown in Fig. 1) comprises a magnetic circuit 1, a first section 2
of a primary winding, a second section 3 of the primary winding, al and xl
the in and out of the winding of the first section, a2 and x2 - the in and out
of
the winding of the second section of the primary winding, RH1 - the resistance
of a load connected to the first section, RH2 - the resistance of a load
connected to the second section of the primary winding. The two sections of
the primary winding are wound on the magnetic circuit l: the first section 2,
the second section 3 thereon in one direction, and they have an identical
number of turns. The outs x~ and x2 of the windings are connected to each
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other in a series circuit, while the ins a~ and a2 of the windings are
separately
connected to a power supply. A load resistance is connected parallel to each
section of the winding: RH~ in the path of the current from the power supply
to the first section of the winding and to the point of connection of the
windings of the sections, and RH2 correspondingly to the second section of the
primary winding.
A transformer in accordance with the invention according to the
embodiment shown in Fig. 2 is made similar to the transformer according to
the embodiment shown in Fig. 1. A distinction is in the presence of secondary
winding 4, which is wound in a third layer on the sections 2 and 3 of the
primary winding on the same core of the magnetic circuit 1. A and X
designate the inlet and outlet (in and out of the phase) of the secondary
winding, RH - the resistance of the load connected to the leads A and X of
the secondary winding.
A transformer in accordance with the invention according to the
embodiment according to Fig. 3 is made similar to the transformer according
to the embodiment shown in Fig. 2. A distinction is that the sections of the
primary winding are wound in opposing directions. The out of the winding of
the first section x~ and the in of the winding of the second section a2 are
connected to each other in a series circuit, the other leads of the sections
al
and x2 serve as inlets for the power supply.
A transformer in accordance with the invention according to the
embodiment shown in Fig. 4 is made similar to the transformer according to
the embodiment shown in Fig. 2. A distinction is that the sections of the
primary winding 2 and 3 are wound on two cores of the magnetic circuit 1.
The sections are connected to each other via opposite leads - the out of the
winding of the first section and the in of the winding of the second section.
Secondary winding 4 is wound on both sections of the primary winding and
encompasses both cores of the magnetic circuit.
A transformer in accordance with the invention according to the
embodiment shown in Fig. 5 is made similar to the transformer according to
the embodiment shown in Fig. 4. A distinction is that the two sections of the
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primary winding are wound in opposing directions, the outs x~ and x2 of the
windings of the sections are connected to each other in a series circuit,
while
the ins al and a2 of the windings of the sections serve as inlets for the
power
supply.
5 A transformer according to the embodiment shown in Fig. 6, in
accordance with the invention, is made similar to the transformer according to
the embodiment shown in Fig. 4. A distinction is that the in of the first
section a~ and the out of the second section x2, and also the out of the first
section xt and the in of the second section a2 are connected to each other,
and
10 the points of their connection serve as inlets for the power supply.
A transformer according to the embodiment shown in Fig. 7, in
accordance with the invention, is made similar to the transformer according to
the embodiment shown in Fig. 6. A distinction is that the sections are wound
in opposing directions, by the ins a~ and a2 and by the outs x~ and x2 the
windings of the sections are connected to each other, and the points of their
connection serve as inlets for the power supply.
The principle of operation of the proposed transformer according to the
embodiment shown in Fig. 1 is as follows.
I. Open circuit (no-load conditions)
The ins ar and a2 of the windings of sections 2 and 3 are separately
connected to a power supply U, the outs xl and x2 of the windings of those
same sections are connected to each other in a series circuit. Wherein a
current i flows through the windings of those sections, this current causing
the
occurrence of a magnetomotive force mmf in each section of the winding
which is equal to iw. Since the fluxes in each section are equal and directed
in
opposing directions they are mutually compensated and reversal of
magnetization of the core does not occur, but as a consequence of
maintenance of the principle of superposition of magnetic fields in a magnetic
circuit, the latter interacts with the fields on a microscopic level which
results
in stressed interaction of a domain structure and a change in the magnetic
permeability of the material of the magnetic circuit. Thus, a change of the
current passing through the sections of the primary winding in time results in
a
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11
change of the permeability, while a change of the latter causes an emf to
appear in those windings between the point of connection of the sections and
the ins of the windings, but shifted by phase in time relative to the current
passing from the supply source. Due to this, the voltage at the output of the
transformer is increased by 10-20 times with actually just one primary
winding.
II. Operating mode (with a load connected)
The load resistance RHl is connected in the path of the current i from
the power supply U to the first section 2 of the winding and to the point of
connection of the outs of the sections, the load resistance RH2 is connected
accordingly to the second section 3 of the winding. The current i from the
power supply is passed through the formed closed loop, wherein the primary
current i is increased in each loop proportionally to the load RH, which
results
in a change of the emf in the loop - an increase of the emf.
At a low load resistance (equal to the resistance of the winding) the
voltage U will be equal to the voltage drop on the winding, when the load
resistance tends to increase to infinity, the secondary voltage U will
increase
proportionally, as a result of which the emf at the output of the transformer
will increase dozens of times when there is one primary winding.
The principle of operation of the transformer according to the
embodiments shown in Figs. 2-7 is similar to the principle of operation of the
transformer according to the embodiment shown in Fig. 1.
A distinction lies in the presence of a secondary winding 4. Since the
primary winding for the mmf in those embodiments remains open, a no-load
emf is always induced therein, i.e. a self inductance current is not created
in
the winding and all the mmf energy is provided as. an emf of the secondary
winding. Under such conditions, the intensity of the electric field per unit
of
length of the conductor of the winding in the secondary winding can exceed by
ten times the intensity of the electric field in the primary winding, which is
set
by the power supply. As a result the secondary winding can have a fewer
number of turns as compared with the primary winding, while the voltage is
dozens of times greater than the mains voltage. Wherein the form of the
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voltage and current in the secondary winding repeats the form of the voltage
and current in the primary winding.
Fig. 8 shows a stylized dependence of the increase of current and voltage
in the primary and secondary windings of a transformer with a ferrite magnetic
circuit.
It should be noted that the permeability ~. of the magnetic circuit
changes in time in the following manner with a sinusoidal form of current: it
increases from 0 to ~c/4, then from ~/4 to ~/2 it drops, and from ~/2 to n3/4
the speed of restoration of the permeability again increases and from X3/4 to
~
the restoration of a is slower. As a result of such a change of the magnetic
permeability, an emf is induced in the secondary winding at a doubled
frequency and there is a complete period of the secondary current for one half-
period of the current in the primary winding.
Fig. 9 shows a stylized dependence of an increase of current and voltage
in the primary and secondary windings of a transformer with a magnetic circuit
of sheet steel. With this type of magnetic circuit there is a shift of the
form of
the primary and secondary current curve from ~/6 to n/4 while the form of the
current is maintained.
The transformation ratio for each type of transformer was experimentally
detern>ined.
Concrete examples of operation of different types of transformers are
given below in order to better understand the invention. The same results
were obtained with embodiments of transformers for which examples are not
provided.
Example 1. M600HH-8 K100-60-15 ferrite' rings were used as the
magnetic circuit. Two sections of the primary winding, one over the other,
were wound on a core of the magnetic circuit assembled from four rings. The
outs of the windings of both sections were connected in a series circuit, a
load
resistance RH was connected parallel to each section - one end to the point of
connection of the sections, the other - to the ins of the sections, the ins of
the
windings of each section were connected to the power supply. The number of
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turns in the sections was identical and equal to 60. The transformation ratio
for this transformer was 11. The results of measurement of the voltage at the
output of the transformer are presented in Table 1, example 1.
Similar results were obtained when the transformer was made with a
ferrite U-shaped magnetic circuit.
Example 2. A ring-type magnetic circuit made from sheet steel and
designed for a power of 2.5 kW was used as the magnetic circuit. Two sections
of the primary winding were wound on the core of the magnetic circuit,
wherein both sections were wound in one direction with their outs connected
in a series circuit, the ins of the sections connected to the power supply. A
secondary winding was wound on the primary winding (the direction in which
it is wound does not affect the operation of the transformer).
The transformation ratio was detern>ined experimentally and was equal
to 5.
The number of turns of one section of the primary winding was 110, the
number of turns of the secondary winding was also equal to 110, the diameter
of the wires in the primary and secondary windings was identical and equal to
1.2 mm. A load was connected to the leads of the secondary winding. The
voltage was measured at the input of the primary winding and at the output of
the secondary winding, i.e. on the load. The results of measurements are
presented in Table l, example 2.
Example 3. U-shaped ferrites were used as the magnetic circuit. The
magnetic circuit was assembled from four units. Two sections of the primary
winding were wound on the two cores of the magnetic circuit, each section on
one core. The sections were wound in opposing directions, but with an
identical number of turns. The total number of turns in the primary winding
was 120. The outs of the windings of the sections were connected in a series
circuit, the ins were connected to a power supply. A secondary winding,
encompassing both cores, was wound on the primary winding. The number of
turns in the secondary winding was 120. The transformation ratio was
determined and found equal to 10. The results are presented in Table 1,
example 3.
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Example 4. A U-shaped magnetic circuit made from sheet steel was
used as the magnetic circuit. Two sections of the primary winding were wound
on both cores of the magnetic circuit, each section on one core. The sections
were wound in one direction, the number of turns in each section was 120.
The out of the winding of the first section and the in of the winding of the
second section, and also the in of the winding of the first section and the
out
of the winding of the second section were connected to each other, and the
points of their connection were connected to the power supply. The secondary
winding was wound on the primary winding, the number of turns in the
secondary winding was 120.
The transforniation ratio of this transformer was 8.5. The results of
measurement are presented in Table 1, example 4.
Table 1
Voltage at the output of the transfornier
U~,~ary, V 100 200 300 400 500 600 700 800 900
Usecondary~ V
Example 1100 2200 3300 4400 5500 6600 7700 8800 9900
1
Example 2 500 1000 1500 2000 2500 3000 3500 4000 4500
Example 3 1000 2000 3000 4000 5000 6000 7000 8000 9000
Example 4 850 1700 2550 3400 4250 5100 5050 6800 7650
Industrial Applicability
Samples of all types of transformers were made and have been working
for from three to five years. All these samples were tested and can serve as
electrical engineering equipment in laboratory practice and in industrial
enterprises.
