RU2328051C2 - Transformer - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is related to electric equipment and may be used in transformers for supply of stabilised voltage for sources of power supply. Transformer consists of the first, second and third shoulders, which are parallel to each other and have at least one first primary winding and at least two secondary windings. Each of windings bears a separate shoulder. Shoulders are installed sequentially. One of the secondary windings is installed between two other shoulders. Two shoulders are connected to capacitor with creation of resonance circuit. Magnet link between two secondary windings is different from magnet links between primary winding and every of secondary windings. Flow that is excited with the first primary winding is anti-parallel to flow that is excited by the second secondary winding. Supply voltage may be sent to the primary winding, and transformer maintains current and voltage in secondary windings.

EFFECT: simplification of design.

23 cl, 8 dwg

Description

FIELD OF THE INVENTION

The invention relates to power sources, in particular to transformers for supplying a stabilized voltage.

State of the art

Power supplies are needed to supply electrical devices with stabilized voltage that differs from the mains voltage, for example, 110 V or 220 V. The main element of the power source is a transformer that converts the input voltage to the output voltage. In conventional transformers, the output voltage is a multiple of the input voltage, and the multiplicity factor is given by the ratio of the number of turns of the primary winding and the number of turns of the secondary winding that are magnetically coupled to each other. In addition, the voltage decreases with increasing load in the secondary winding with increasing current, and the secondary windings have internal resistance.

When used in the field of welding, conventional power sources exhibit the effect that the current through the light arc strongly depends on the distance of the electrode from the material to be welded. In particular, for a welding method with a consumption of electrodes, this requires very sensitive power management to eliminate irregularities in the weld. In addition, the weight and thereby the need for core material of the transformers are high and should be reduced with regard to portable welding devices.

Undesired effects of load and input voltage on the output voltage are usually compensated by an electronic control device that measures the output voltage and controls the input voltage. If the decrease in output voltage is measured, the input voltage rises or vice versa.

In addition, high-frequency components are created if the input voltage is provided by an inverter power source. Therefore, typical power supply applications require filtering to remove high frequency components.

WO 99/17316 discloses a transformer having a central arm connected in parallel with the primary and secondary windings. In addition, the transformer is provided with a gap in the central arm and is controlled by an external control device.

GB 803911 discloses a transformer having an air gap in the central arm and further comprising a secondary arm that is divided into two branches. Each of the two branches carries one secondary winding, while the two windings are connected to each other and feed the load.

GB 2033163 A discloses a transformer having an air gap between the primary and secondary windings located on two adjacent arms. The resonant circuit does not open in the transformer.

WO 97/29494 describes a transformer with several taps in the secondary windings that are selectively connected to control the output voltage.

Another possibility of converting the output voltage of an alternating current is to rectify it into a direct current voltage and control the direct current voltage using Zener diodes or similar devices in order to obtain a stable output voltage.

These technologies require a huge number of control and stabilizing elements.

Disclosure of invention

It is desirable to have a power supply with a reduced number of elements, and preferably a transformer, providing an output voltage that is broadly independent of the load and the supply voltage level. In addition, it is desirable to have a transformer capable of generating waves and providing current limitation.

Therefore, the invention relates to a transformer according to paragraph 1 of the claims that performs the above task.

The invention relates to a transformer having a stabilized output voltage, while the stabilization effect is achieved using electric and magnetic structures. The output voltage is stabilized by means of a control magnetic connection between at least one primary (input) winding and secondary (output) windings.

At least one primary winding and at least one first secondary winding and one second secondary winding are wound around one of the three arms, respectively, and magnetically connected from above by an air gap and from below by a clamp. The resonant circuit formed by the secondary windings and the capacitor provides high saturation of the magnetic connection between the secondary windings. Resonance is limited by the air gap, which also controls saturation, as well as the load current that the secondary windings supply to the connected load. If the behavior is mainly characterized by the influence of the resonant circuit, then the inductance related to the secondary windings forming part of the resonant circuit is greatly increased. Under changing conditions, i.e. the changing load or the changing input voltage on at least one primary winding the total flow in the secondary windings and therefore the output voltage on the secondary windings is kept constant by controlling the saturation of the magnetic connection, which mainly depends on the resonant circuit at low loads and depends from loading at high loads. In other words, the magnetic coupling between the primary winding and the secondary windings, and thus the power transfer between the primary winding used as the input winding, and the secondary windings used as the output windings, is caused by the load, since the additional flow generated by the load and the flow generated resonant circuit, control the saturation level of the magnetic coupling. In addition, the attenuation of resonance increases with increasing load. This control behavior can be influenced by an air gap, which has a direct effect on magnetic coupling.

In one embodiment, one primary winding carries the first shoulder, while at least two secondary windings carry two shoulders, respectively. The secondary windings are connected to a capacitor to form a resonant circuit. The shoulders are magnetically connected at their respective ends with two clamps, with at least one clamp containing an air gap between the respective shoulders bearing the secondary windings. In this embodiment, the stabilization effect is achieved with a minimum number of magnetic arms.

In the first load range, the voltage is constant and therefore the effects of the input voltage or load are compensated. In the second range with a higher load, the voltage decreases rapidly and thereby limits the current. This operating range can be used for welding applications since the current is constant over a wide range and thereby compensates for changes caused by changes in the distance between the electrode and the welding surface. Therefore, the transformer provides a very stable arc without additional control means, and thus the seam is more uniform compared to the results achieved using conventional welding power sources. In addition, the amount of core material can be reduced compared to conventional welding devices with the same welding power.

In addition, using the transformer according to the invention, a wave-forming effect is provided, which reduces high-frequency interference, for example, if an inverter power supply is used. In addition, you can more easily control the speed of DC motors without the need for expensive rectifier devices.

The second embodiment includes an additional arm and an additional primary winding. Two primary windings are located on the two outer shoulders, and two secondary windings are located on the inner shoulders. The two primary windings are electrically connected to each other, and the secondary windings are electrically connected to each other. This embodiment provides a symmetrical structure and provides a constant output voltage on the secondary windings in a wide range of input voltages supplied to the primary windings.

The secondary windings preferably have intermediate taps to select the desired output voltage by selecting the number of turns of the secondary windings on both sides of the intermediate taps. As an alternative solution, the transformer contains a third and fourth secondary windings, while the first and second windings form a resonant circuit together with a capacitor, and the third and fourth windings provide output voltage. Thus, it is possible to separate the two functions of the secondary windings.

In addition, the secondary windings supplying the output voltage can be connected in series. Thus, a higher overall output voltage can be provided. In addition, it is possible to connect the secondary windings in series, due to which the inductances of the corresponding secondary windings add up. Thus, a lower capacitance can be used for resonance at the desired frequency, for example, a supply frequency, for example, 50 or 60 Hz. In an embodiment of the invention, in which the voltage is supplied from an inverter power source and therefore is a high-frequency voltage, the capacitor values, as well as the magnitudes of the inductances provided by the secondary windings and used for the resonant circuit, can be significantly reduced compared to using frequencies of 50/60 Hz.

The magnetic coupling of the shoulders is preferably provided with two clamps, one for each side of the shoulders. These clamps may contain an air gap or magnetic material, which determines the different quality of the magnetic coupling between the arms carrying the secondary windings, and the magnetic coupling between the other respective arms. Thus, it is possible to simply control the saturation level and transformer characteristics due to saturation. In addition, the transformer can be manufactured using a standard method.

The winding direction in all windings may be the same. It also facilitates the manufacturing process of transformers.

The two primary windings are preferably connected in series. This reduces the number of necessary turns for a given output voltage at a given input voltage on the secondary windings.

The magnetic coupling between the arms carrying the windings, which form part of at least one resonant circuit, preferably provides a magnetic flux of scattering and ferromagnetic losses, which both can be used to control the attenuation of the resonant circuit and thereby its behavior and influence on the stabilization characteristics of the transformer.

All primary windings and all secondary windings preferably have the same number of turns, respectively. This provides a completely symmetrical structure and simplifies the manufacturing process.

To influence the magnetic coupling and saturation of the magnetic material of the transformer, the cross section of the shoulders bearing the secondary windings may be different from the cross section of the shoulders bearing the primary windings. It also allows you to control the saturation and thus the characteristics of the transformer.

An embodiment containing an additional primary winding provides a more flexible connection of the transformer to the supply network.

Brief Description of the Drawings

The drawings show:

figa is a first embodiment of a transformer having three arms containing a primary winding and two secondary windings;

fig.1b - the second embodiment of a transformer having four shoulders containing two primary windings and two secondary windings;

figure 2 is a third embodiment of a transformer in which two secondary windings are used as a resonant circuit, each containing an intermediate tap;

figure 3 is a fourth embodiment of a transformer in which two secondary windings form a resonant circuit, and two other windings are used as the output winding;

4 is a change in the output voltage depending on the changing load for three transformers according to the invention, having different widths of the air gap;

figure 5 - characteristics of wave filtering and wave formation according to one embodiment of the invention;

6 is a change in the output voltage depending on the changing input voltage at various loads;

7 - characteristics of the output current depending on the change in load resistance.

The implementation of the invention

On figa shows a diagram of a first embodiment of a stabilized transformer according to the invention. The transformer contains three arms 1, 2, 3, which are parallel to each other and magnetically connected using two clamps 9, 9 '. This structure can be made of a conventional three-core core with a clamp. Two secondary windings 5, 6 are electrically connected to the capacitor 7 to form a resonant circuit having two inductors represented by secondary windings, each of which is located on a separate arm. The magnetic connection between the shoulders carrying the secondary windings 5, 6 contains an air gap 8. The primary winding 4 carries the first arm 1, while the secondary windings 5, 6 carry the arms 2 and 3, respectively. One of the shoulders carrying the secondary windings 5, 6 is located as the central shoulder of the three-core core.

1b shows a diagram of a second embodiment of a stabilized transformer according to the invention. The transformer contains four arms 10, 12, 14, 16, which are parallel to each other and magnetically connected. The shoulders 10-16 have the shape of a rod of the same length. Each shoulder has two ends, an upper end and a lower end, while all the upper ends are magnetically connected using the upper yoke 50, perpendicular to the shoulders, and all lower ends are connected using the lower yoke 52, which is also perpendicular to the shoulders 10-16 and thereby parallel the upper yoke 50. Among the shoulders 10-16 should distinguish between two outer shoulders 10, 12 and two inner shoulders 14, 16.

A first primary winding 20 with a first number n _{p of} turns is wound around the first outer arm 10, and a second primary winding 22 having a second number of n _p 'turns is wound around a second outer arm 12. Both primary windings 20, 22 are electrically connected in series, and the input the voltage U _p can be applied to the primary windings 20, 22. The first primary winding 20, excited by this input voltage U _p, creates a magnetic flux in the first outer arm 10, which is counter-parallel to the magnetic flux generated by the second primary skein 22 in the second outer shoulder 12. You can also connect both primary windings counter-parallel, which leads to the same result. As an alternative solution, two primary windings can be connected in parallel, while the primary windings have winding directions that are opposite to each other.

The first 30 and second 32 secondary windings are wound around both inner shoulders 14, 16, respectively, and have the same winding direction. The secondary windings 30, 32 are connected in parallel to each other on one side using a direct electrical connection, and on the other side of the secondary windings using a capacitor C 40. The value of the capacitor C is selected to form a resonant circuit with the first and second secondary windings at the output voltage frequency, e.g. 50 Hz power supply.

When applying the input voltage U _p to the first and second primary windings 20, 22, which are connected in series, each of them introduces a magnetic flux into the first 10 and second 12 of the outer arm, respectively. Due to the magnetic coupling provided by the upper 50 and lower 52 clamp and the electrical connection, the fluxes generated by the input voltage are added to the outer arms 10, 12. In addition, the flux induced by the current passing through the second windings 30, 32 is folded into the inner arms 14, 16 when a load is applied to the secondary windings.

Between the first and second inner arms 14, 16, the upper yoke 50 comprises a section containing an air gap 60. In this section, the magnetic conductivity or magnetic resistance is different from the magnetic conductivity or magnetic resistance in the rest of the clamp. Magnetic conductivity or magnetic resistance means effective permeability and therefore the ability of magnetic coupling, i.e. clamps, concentrate the magnetic flux in the material. This ability is strictly dependent on the effective permeability of the clamp, which depends on the magnetic permeability, magnetic coupling geometry and effects caused by the scattering field, for example, air gaps.

Differences in magnetic conductivity and thus effective permeability can also be caused by a section of the clamp having a larger or smaller cross section. In particular, the narrowing zone of the clamp causes a higher flux density and therefore the material conducting the magnetic flux has a higher saturation level than the rest of the material. In addition, a section containing a material having a low permeability, or a magnetic material containing a lower level of maximum saturation, leads to the desired dependence of the magnetic coupling on the flow in the clamp.

When an input voltage is applied to the two primary windings 20, 22, an electromotive force EMF is induced in the first 30 and second 32 secondary windings, which are located near the primary windings 20, 22.

Some current is generated by electromagnetic induction in the first 30 and second 32 secondary windings and in the capacitor C 40 and therefore an additional electromotive force of self-induction is induced in two secondary windings 30, 32. This electromotive force of self-induction is added to the emf induced by the current flowing through the primary windings 20, 22, and therefore the voltage available on the capacitor C 40 is further increased. If the voltage present on the capacitor 40 increases, then the current passing through the secondary windings 30, 32 increases, which leads to a resonant increase in the electromotive force of self-induction. The limit of the electromotive force of self-induction depends on the saturation characteristics of the magnetic material of the clamps 50, 52 (and shoulders), which are not linear with respect to the inducing magnetic field. Thus, the voltage U _s provided by the secondary windings 30, 32 is not linear with respect to the input voltage U _p , which is applied to the primary windings 20, 22, and, in addition, the ratio of input and output voltages is characterized by a saturation process in which resonance the circuit compensates for changes in the load on the secondary (i.e., output) windings and a change in the input voltage applied to the primary windings.

In the embodiment shown in FIG. 1b, the number of turns n _{p of the} first primary winding is equal to the number of turns n _p 'of the second primary winding. The number of turns n _{s of the} first secondary winding is equal to the number of turns n _s ' of the second secondary winding. In this example, n _p = n _{s is} taken for convenience.

The first 30 and second 32 secondary windings represent two inductors that are connected in series. Therefore, their inductances are added and connected in parallel with the capacitor C 40. The inductance depends on the geometry of the secondary windings 30, 32 of the arms 14, 16, respectively, as well as on the number of turns n _s and n _s ', in addition, the inductance depends on the effective permeability, which varies in depending on the degree of saturation of the magnetic material of the arms 30, 32. The material of the clamps 50, 52 is also saturated at high magnetic fluxes. The combined inductance of the first and second secondary windings 30, 32 and the value of the capacitor C 40 are selected in accordance with the desired resonant frequency of the output voltage U _s , for example, 50 Hz. Under the assumption that the input voltage U _p contains significant parts of the frequency near or at the resonant frequency, the secondary windings will be excited in resonance with this frequency. The amount of energy exchanged between the capacitor 40 and the inductance of the secondary windings 30, 32 is a magnetic excess and is limited by the maximum magnetic flux at which full magnetic saturation of the magnetic material is achieved in the clamp section having the highest flux density. In addition, the resonance is attenuated by the load occurring at the output of the secondary windings 30, 32, and losses due to magnetic scattering.

Suppose that the input voltage U _{p is} applied to the primary windings, and the load occurring on the secondary windings 30, 32 is initially negligibly small. In this case, the magnetic coupling represented by the upper and lower yokes is saturated with an almost non-attenuated resonant circuit formed by the secondary windings 30, 32 and the capacitor 40.

The resonant frequency of the resonant circuit should be approximately equal to the frequency of the input voltage supplied to the primary windings, and therefore, the value of the capacitor 40 (or the inductance of the secondary windings) should be selected so as to meet this condition. The output voltage U _s on the secondary windings 30, 32 is limited by the degree of maximum saturation of the yokes 50, 52, in particular, of the section 60 between the two inner arms 14, 16. As the load increases, the resonant circuit is weakened by the load and therefore has a reduced effect on saturation. A large flux caused by (load) current flowing through the secondary windings 30, 32 (and the load) has an increased effect on saturation. Both effects cancel each other out and, therefore, a decreasing or increasing load is balanced by the increasing or decreasing influence of the resonant circuit, which leads to an almost constant output voltage U _s on the secondary windings 30, 32 when the load changes.

The curve of the change in the output voltage U _s depending on the load change (and thereby depending on the output current) is affected by additional air gaps 60, 260, 260 'in one (50) or in both clamps 50, 52 taking into account the magnetic characteristics of the material as well as ferromagnetic losses.

Figure 2 shows a third embodiment of a transformer according to the invention. It also contains four shoulders 110-116 connected by two yokes 150, 152, and contains two primary windings 120, 122, which are connected in series and symmetrically located on the outer shoulders 110, 112. In addition, two secondary windings are also symmetrically located on the inner shoulders and while connected in series with a capacitor 140 to form a resonant circuit. Between the inner shoulders 114, 116, one yoke 150 is interrupted by an air gap 160.

In contrast to the embodiment shown in FIG. 1, the secondary windings 130, 132 comprise each intermediate tap 170 from which the output voltage U _s is removed. The resonant circuit is formed by full secondary windings 130, 132 and capacitor 140, while the output voltage U _{s is} provided by only a part of the secondary windings 130, 132, respectively. The ratio between the turns contained in this part of the respective secondary windings and the number of turns of the complete secondary windings 130, 132 makes it possible to determine the relationship between the input voltage U _p and the constant output voltage U _s . In addition, in this way, the influence of the resonant circuit on the equilibrium between the attenuation of the resonant circuit and the saturation of the yokes 150, 152 can be changed.

Figure 3 shows a fourth embodiment of a transformer according to the invention. This embodiment has a four-arm structure, as in the embodiments shown in FIGS. 1 and 2, however, the secondary windings 230, 232, 234, 236 are divided into two functional parts that are not electrically connected to each other. The first functional part is the resonant circuit formed by the capacitor 240 and the first and second secondary windings 230, 232. The second functional part of the secondary windings consists of a third and fourth secondary windings 234 and 236, which are both symmetrically located on two inner arms 214, 216. These third and the fourth secondary windings 234 and 236 are electrically connected to each other and provide an output voltage U _s . With this structure, the output voltage can be selected completely independently of the characteristics of the resonant circuit, which is formed by the first and second secondary windings 230, 232 and capacitor 240. The number of turns in the windings is chosen symmetrically, i.e. n _p = n _p ', n _s = n _s ' and n _o = n _o '. The number of turns of at least one pair of windings may not coincide depending on the application and the desired behavior characteristics. Clamps 250, 252 are provided between the inner arms 214, 216, each of which includes an air gap 260, 260 ′ providing the desired effect on the saturation characteristics and the attenuation of the resonant circuit.

4 is a graph illustrating the effect of the width of the air gap. The relationships between the secondary output voltage U _s provided by the secondary windings 30, 32, 130, 132, 230, 232 of the transformer according to the invention and the current I _s flowing through a load connected to the secondary windings are shown. For the first range of the output current I _s , which is indicated by the position A, the voltage remains almost constant with the voltage U _c . In the second range (V), the output voltage U _s drops rapidly with a slight increase in the output current I _s . This behavior can be used to protect against short circuit or in overload situations, as well as to supply a constant current with an operating point in the B range, for example, for welding machines.

The behavior of the transformer with respect to the output voltage U _s and the output current I _s in the range B can be interpreted as the behavior of a source of unchanging current. In particular, taking into account curve 2, the current remains almost unchanged with the value of I _c , while the voltage varies in a wide range between U _s and 0. The transformer according to the invention, operating in this operating range or having an operating point in the area of this sharp drop in output voltage U _s , especially suitable for welding applications. When a constant current I _c, is provided on the output transformer, the electric arc remains stable and thus less sparks generated and the result is a homogeneous welding. In general, for the power sources used to create an electric arc with varying loads, these characteristics of the transformer according to the invention provide very stable output characteristics. The characteristics of this second (closed or corresponding to a changing current source) zone B can be selected by changing the width of the air gap 60, 160, 260, 260 ', while curve 1 shows the behavior for a large air gap, for example, 3 mm, curve 2 shows the characteristics unchanging current for a narrow air gap, for example, 2 mm, and curve 3 shows the characteristics for a very small air gap, for example, 0.5 mm. It should be noted that the core structure according to curve 1 causes a greater magnitude of the scattering magnetic flux than the core structure according to curves 2 or 3 for the total flux contained in the respective clamps. Therefore, the core structure according to curve 1 has a stronger effect on the attenuation of the resonant circuit, since the magnetic flux of scattering forms the main part of the effect of attenuation on the resonant circuit. In addition, a higher dissipation flux at moderate loads affects the magnetic coupling between the respective opposite primary and secondary windings 20, 36 and 22 and 34, respectively, and therefore affects the stabilized output voltage at high loads.

In the case of a negligibly small load connected to the secondary windings 30, 32, the stabilized output voltage on the secondary windings is determined by the maximum saturation of the magnetic material and the magnetic flux of scattering, while the increased load introduces the attenuation into the resonant circuit, keeping the voltage constant due to the reduction of the balancing effect between the resonant circuit and the saturation (i.e., magnetic coupling) of the clamp section between the two inner arms 14, 16.

As shown in FIG. 5, the use of a resonant circuit also improves the frequency stability of a transformer endowed with a waveform, since the resonant circuit has the characteristics of a bandpass filter. The sign of wave formation allows you to have a sine curve at the transformer output, which is almost independent of the symmetrical shape of the input wave or the load of the secondary windings. Any symmetrical waveform supplied to the input U _in (i.e., primary windings) is filtered, and as a result, the output voltage U _{out of the} transformer contains a sinusoidal shape.

6 shows the output voltage characteristics of a transformer according to the invention. The curves show the dependence of the voltage U ₂ on the secondary windings on the voltage supplied to the primary windings 20 22, which is designated as U ₁ . When the load connected to the secondary windings 31, 32 is negligible, and the input voltage supplied to the primary windings 20, 22 reaches a certain value, which is denoted as b, then the voltage on the secondary windings reaches a limit value, denoted as d, which directly related to the saturation limit of the magnetic circuit. If the voltage supplied to the primary windings increases above b, then the electromotive force is induced in one secondary winding 30 adjacent to the corresponding primary winding 20, in accordance with the increase in voltage on the primary windings 20, 22. The electromotive force is equal to the total vector of two electromotive forces induced in the secondary winding under consideration by the adjacent primary winding 20 and the remote primary winding 22. For another secondary winding 32, this process is provided in a symmetrical manner in the arm 16 around which another secondary winding 32 is wound, while the flows are induced by the corresponding adjacent primary winding 22 and the corresponding remote primary winding 20. It should be noted that the flux induced in the inner shoulder (for example, 14) by the corresponding adjacent primary winding (for example, 22) is always greater than or at least different from the flux induced by the corresponding far winding (for example, 20) due to the air gap 60 between the shoulders 14, 16. As mentioned above, you can use any means that can reduce the magnetic wire spine, in the sections between the inner yoke legs 14, 16. Therefore, the compensation is carried out between the saturation current of the load generated at the secondary windings and saturation created by the resonant circuit. Therefore, the output voltage stabilizes at an almost constant level c ... d, while the input voltage on the primary windings can vary over a wide range of b ... a.

Due to the moderate current in the resonant circuit formed by the secondary windings 30, 32 and the capacitor C 40, the output voltage on the secondary windings 30, 32 is kept constant, since the current in the resonant circuit having a phase difference of almost + 90 ° relative to the phase of the current through the load has a higher level than the load current in a small load.

Reducing the input voltage U ₁ results in less magnetic flux and thus to a lower level of saturation in the magnetic connection 50, 52, 60. A lower level of saturation causes a better connection at the yoke section 60 between the two inner legs 14, 16 as well as to higher current oscillations in the resonant circuit, since the resonant circuit has less attenuation. Due to this, the saturation level increases until the increase in attenuation due to saturation is not balanced by the lower flux induced by the primary windings 20, 22, due to the lower input voltage. This balancing effect leads to a stabilized output voltage, which over a wide range is independent of the input voltage.

6 also shows the relationship between input voltage and output voltage for various loads. Curve 1 shows the relationship between U ₁ and U ₂ at a negligible load, curve 2 shows the relationship between U ₁ and U ₂ at a moderate load, and curve 3 shows the relationship between U ₁ and U ₂ at a heavy load, which is greater than the loads related to curves 1 and 2. As indicated above, at a certain input voltage U ₁ = b corresponding to the output voltage U ₂ = d, an equilibrium state is reached, and when the input voltage increases, the output voltage remains almost constant. It should be noted that for a wide range of b ... and the input voltage U _1, U ₂ input voltage changes only in a small range d ... c. The range in which the output voltage U ₂ is almost constant begins at the minimum input voltage U ₁ , which depends on the load connected to the output (i.e., the corresponding secondary windings) of the transformer. For a large load (curve 3), the minimum input voltage is higher than the minimum voltage for a small (curve 2) or negligibly small (curve 1) load connected to the secondary winding.

Figure 7 shows the behavior of the transformer according to the invention with changing loads in the form of a graph of the change in the input current I ₁ supplied to the primary winding (windings) and the output current I ₂ generated in the secondary windings with a varying load R.

At high loads equivalent to R in the range 0 ... R _r , a stable current I _{s is} provided at the output. This corresponds to the case of “overload” shown in FIG. 4, range B. Under loads with a resistance greater than R _r , the current is continuously reduced. Although not shown in this graph, the corresponding output voltage on the secondary winding (s) remains constant. The range for R> R _r is equivalent to range A in FIG. 4. To better understand the characteristics of the transformer, FIG. 7 should be considered in conjunction with FIG. 4, while FIG. 4 shows the characteristics of the output voltage, and FIG. 7 shows the characteristics of the output current with a changing load (i.e., with a changing output current) .

The core of the transformer may contain a layered, sintered or molded magnetic material that is saturated at high magnetic fluxes. Materials having different saturation characteristics can be provided for different parts of the transformer, i.e. material 1 for the inner shoulders, material 1 'for the outer shoulders and material 2 for magnetic coupling between the two inner shoulders in the four-arm embodiment. Magnetic materials such as permalloy or other ferrite materials can be used, and they can be selected depending on the frequency range used. The transformer according to the invention can also be used for applications with high frequency, for example, with an inverter power source, since the waveform characteristics of the transformer provide a sinusoidal shape of the output wave. In the case of high-frequency input and output voltages, the core material used for shoulders and clamps can be selected accordingly. The core cross section is preferably constant and may have a square, round or other shape. The air gap can be created using the section of the yoke, having a reduced length, which leads to the creation of a gap and thereby provides an effect on magnetic coupling. In addition, ferromagnetic materials or a clamp section with a reduced cross-section may be used instead of or in combination with an air gap in order to achieve the desired magnetic properties.

In the illustrated embodiments, only one capacitor is used. More than one capacitor may also be used in combination with one or more secondary windings. The capacitor (s) and the secondary winding (s) form a resonant circuit, which can be obtained by parallel or series connection or by a suitable combination thereof. If there is more than one capacitor and thus more than one resonant circuit, the corresponding resonant frequencies can differ from each other, while the resonant circuits can oscillate at least partially independently of each other.

Magnetic materials having magnetic hysteresis can also be used to effect the attenuation of the resonant circuit with the conversion of part of the energy oscillating between the capacitor and inductance into magnetic losses and thereby into heat. In addition, the resistance of copper windings can lead to a significant loss of vibrational energy in the resonant circuit, and it should be taken into account when considering the attenuation that affects the resonant circuit.

The primary and / or secondary windings may contain several intermediate taps to simplify the matching of the transformer in accordance with changing voltage or load conditions and in accordance with various applications.

Claims (23)

1. A transformer containing: at least the first (1), second (2) and third (3) arms, with all arms aligned substantially parallel to each other, at least one first primary winding (4), at least one first (5) and one second (6) secondary windings and at least one capacitor (7), wherein at least one first primary winding (4) is wound around the first shoulder (1), at least one first secondary winding (5) is wound around a second shoulder (2), at least one second secondary winding (6) is wound around a third arm (3), and the capacitor (7) is connected to at least one winding wound around the second arm (2), and at least one winding wound around the third arm (3), with the formation of a resonant circuit, while the first arm (1), the second arm (2) and the third arm (3) are arranged in this sequence and are magnetically coupled using at least one upper (9) and lower (9 ') magnetic connection connecting the respective ends of the arms, the first (5) and second (6) secondary windings are electrically connected so that the flow excited by the first secondary winding (5) in the second arm (2) is counter-parallel to the flow excited by the second secondary winding (6) in the third arm (3 ), secondary windings (5, 6) providing at least one output voltage, and at least one upper (9) or lower (9 ') magnetic connection comprises a section (8) located between the second (2) and third (3) arms and having a magnetic conductivity different from the magnetic conductivity between the first and second arms. 2. The transformer according to claim 1, in which at least one of the secondary windings contains an intermediate tap (A, A '), on which the output voltage is provided. 3. The transformer according to claim 1, in which the windings providing at least one of the output voltages are connected in parallel or in series. 4. The transformer according to claim 1, in which the capacitor and the first and second secondary windings are connected in series with the formation of a resonant circuit. 5. The transformer according to claim 1, in which at least one upper and lower magnetic connections contain a clamp having an air gap, a section with a cross-section with a material different from the cross-sectional material of the rest, having a permeability different from the permeability of the material of the rest the clamp, and / or the dependence of saturation on the flow in the cross section, different from the similar dependence in the rest of the clamp, with section (8) located between the shoulders bearing the secondary windings (5, 6). 6. The transformer according to claim 1, in which the magnetic coupling between the shoulders bearing the secondary windings (5, 6), is dependent on the load connected to at least one of the secondary windings supplying the output voltage, and on the input voltage, which is supplied to at least one of the primary windings (4). 7. The transformer according to claim 1, in which the resonant circuit forms an active element, so that the element does not depend on the input current or input voltage applied to at least one of the primary windings (4). 8. The transformer according to claim 1, in which at least one magnetic connection between the shoulders bearing the secondary windings, provides a magnetic flux and / or ferromagnetic loss. 9. The transformer according to claim 1, in which the shoulders (2, 3) bearing the secondary windings have a cross-sectional area different from the cross-sectional area of at least one shoulder (1) bearing at least one primary winding. 10. A transformer comprising: at least the first (14) and second (16) inner shoulders and the first (10) and second outer shoulders, with all shoulders aligned substantially parallel to each other, additionally at least one second primary winding (22), while at least one first primary winding (20) is wound around the first outer shoulder (10), at least one second primary winding (22) is wound around a second outer shoulder (12), at least one first secondary winding (30) is wound around the first inner shoulder (14), at least one second secondary winding (32) is wound around a second inner shoulder (16), and the capacitor (40) is connected to at least one winding wound around the first inner shoulder (14), and at least one winding wound around the second inner shoulder (16), with the formation of a resonant circuit, while the first outer shoulder (10), the first inner shoulder (14), the second inner shoulder (16) and the second outer shoulder (12) are located in this sequence and are magnetically connected using at least one upper (50) and lower (52 ) a magnetic connection connecting the corresponding ends of the first and second inner and outer arms, the first (20) and second (22) primary windings are electrically connected so that the flux excited by the first primary winding (20) in the first outer arm (10) is counter-parallel to the flux excited by the second primary winding (22) in the second outer shoulder (3), and at least one upper (50) or lower (52) magnetic connection comprises a section (60) located between the first (14) and second (16) inner arms and having a magnetic conductivity different from the magnetic conductivity between each outer arm and adjacent inner shoulder, respectively. 11. The transformer according to claim 10, in which at least one of the secondary windings contains an intermediate branch (170), on which the output voltage is provided. 12. The transformer according to claim 10, comprising a third secondary winding (234) wound around the first inner shoulder (214) and a fourth secondary winding (236) wound around the second inner shoulder (216), which are electrically connected so that the flow, excited by the third secondary winding (234) in the first inner arm (214), is counter-parallel to the flow excited by the fourth secondary winding (236) in the second inner arm (212), with the third and fourth windings providing at least one output tension, and the first and second I secondary windings (230, 232) are electrically connected to the capacitor (240) to form a resonant circuit. 13. The transformer of claim 10, in which the windings providing at least one of the output voltages are connected in parallel or in series. 14. The transformer according to claim 10, in which the capacitor (40) and the first and second secondary windings are connected in series with the formation of a resonant circuit. 15. The transformer of claim 10, in which at least one upper (50) and lower (52) magnetic connections contain a clamp having an air gap, a section with a cross section with a material different from the material of the cross section of the rest, having a permeability different from the permeability of the material of the rest of the clamp, and / or the dependence of saturation on the flow in the section, different from the similar dependence in the rest of the clamp, with section (60) located between the shoulders bearing the secondary windings (14, 16). 16. The transformer according to claim 10, in which the magnetic coupling between the arms carrying the secondary windings (14, 16) is dependent on the load connected to at least one of the secondary windings supplying the output voltage and the input voltage, which is supplied to at least one of the primary windings (20, 22). 17. The transformer according to claim 10, in which the resonant circuit (40, 30, 32) forms an active element, so that the element does not depend on the input current or input voltage applied to at least one of the primary windings (20, 22 ) 18. The transformer of claim 10, in which the first (20) and second (22) primary windings are connected in series or in parallel. 19. The transformer of claim 10, in which all the primary windings have the same direction of winding and / or all secondary windings have the same direction of winding. 20. The transformer according to claim 10, in which at least one magnetic connection between the shoulders (14, 16) carrying the secondary windings provides a magnetic flux of scattering and / or ferromagnetic loss. 21. The transformer according to claim 10, in which at least two primary windings (20, 22) contain the same number of turns (n _p , n _p ') and / or at least two secondary windings (30, 32 ) contain the same number of turns (n _s , n _s '). 22. The transformer according to claim 10, in which the shoulders (14, 16) bearing the secondary windings have a cross-sectional area different from the cross-sectional area of at least one shoulder (10, 12) bearing at least one primary winding. 23. The transformer according to claim 10, in which at least one additional winding is wound around one of the inner shoulders (14, 16) and is electrically connected to the first and second primary windings (20, 22).

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