WO2011060779A1 - Continuously adjustable transformer - Google Patents

Abstract

The invention relates to a continuously adjustable transformer (200), comprising a transformer core (100), a primary winding (7), a one-layer contactable adjustment winding (30), an adjustment contact (22) that can be moved along the adjustment winding (30), and a contact element (28) connected to an end of the adjustment winding (30). The contact element (28) is arranged outside the transformer core (100) such that the adjustable transformer (200) can be continuously adjusted and is suitable for very high powers.

Description

 Title: Stepless variable transformer

The invention relates to a continuous variable transformer with a

Transformer core, a primary winding, a single-layer, contactable control winding, a variable along the control winding actuating contact and connected to one end of the control winding contact element.

Transformers are used in a variety of ways. Mostly, they serve to match the voltage of a power source to a consumer when it needs a different voltage. An example of such an application is a power supply. The transformer in such a power supply usually consists of a transformer core made of iron, around which two electrical coils are wound in such a way that the current is conducted around the iron core several times. If one applies to the one coil, the so-called primary winding, an alternating current, then electrical energy is transmitted by electromagnetic induction to the second coil, the so-called secondary winding. Here, in an ideal transformer, the ratio of the voltages and currents in both circuits is directly proportional to the ratio of winding numbers. In the case of a real transformer, on the other hand, there are different effects

Voltage and current losses.

In the described basic type of transformer, the voltage is transformed by a constant factor. Often, however, transformers are needed that provide an input voltage to different voltages

transform. A stepless variable transformer is described in the published patent application DE 3744436 A1. However, this is only suitable for small services. For railways and power plants, however, variable power transformers are needed. For this purpose, variable transformers are used, the more

Taps have, with the removal of various output voltages done by on-load tap-changer. There may also be a voltage tap on the exposed turns by means of a sliding contact. These Variable transformers, however, have significant disadvantages. Thus, tap changers or sliding contacts are heavily loaded both mechanically and electrically by the high voltages and currents and the associated sparking and require a high level of maintenance. Another disadvantage is that a voltage adjustment can only be done gradually and additional fine adjustment requires additional technical effort.

The object of the invention is therefore to propose a variable transformer, which is both infinitely adjustable and is suitable for very high powers.

This object is achieved in that the contact element is arranged for connection to a consumer outside of the transformer core. in the

Transformer core itself and in its interior is at one of the

Primary winding applied AC voltage generates a magnetic alternating field. This alternating magnetic field in turn induces eddy currents in electrical conductors within the alternating field. The eddy current losses increase quadratically with the frequency. Due to the arrangement of the contact element outside of the transformer core, the contact element is arranged outside of the alternating magnetic field. As a result, the induction of eddy currents within the contact element is avoided and there are no eddy current losses. Surprisingly, this can significantly improve the efficiency of the variable transformer.

Advantageous embodiments are specified in the subclaims and are explained below.

By the actuator winding forms a coil which is rotatable about its longitudinal axis, the actuating contact need not be guided around the control winding around, but can contact by vertical movement with a rotation of the control winding each point on the control winding.

To amplify the magnetic field generated by the control winding is a

Spool provided, which is in particular ferromagnetic. The ferromagnetic transformer core has as a base a lower horizontal core element, which is connected by means of a vertical core element with an upper core element, so that approximately results in a U-shape rotated by 90 degrees. The bobbin with the adjusting winding is arranged in the intermediate space between the lower horizontal core element and the upper horizontal core element. This results in the usual for transformer cores

rectangular shape, but with the spool core movable with the control winding, i. is rotatable about its longitudinal axis. All core elements including the spool core are preferably made of dynamo sheets to increase the efficiency of the variable transformer.

Between the control coil and the coil core, a bobbin of dielectric material, in particular of polyethylene, is provided, which has a circumferential recess as a guide for the control winding. As a result, the exposed control winding is on the one hand electrically insulated from the spool core and on the other hand firmly held on the spool core, so that the windings can not contact each other. Upon rotation of the adjusting winding and the coil core, the bobbin rotates.

The control winding is connected by means of a connecting conductor with an electrical inner conductor, which is connected to the outside of the transformer core

arranged contact element is electrically connected. This can be a

Be connected to the actuator winding, with a connection to the contact element and with the other connection to the

Alternate contact.

The conductivity of the inner conductor for alternating current is improved by the fact that this consists of a strand of insulated, parallel connected individual conductors,

in particular copper. Around the inner conductor from the spool core

shield, an insulator is provided, which surrounds him.

The bobbin, the coil core and the insulator are each as one

Circular hollow cylinder formed, wherein the coil core in the cavity of the

Bobbin, the insulator in the cavity of the coil core and the inner conductor in the Cavity of the insulator is arranged. As a result, the said elements are electrically isolated from each other and yet arranged compact.

The control winding, the bobbin, the coil core, the insulator and the inner conductor are firmly connected and rotatable together. They are coupled via a gear with a threaded spindle, for driving the actuating contact, in order to effect a rotation of a synchronized vertical movement of the actuating contact along the control winding.

The arranged outside of the transformer core contact element is designed as a sliding contact, in particular as a slip ring with a brush. Due to the sliding contact, the rotatable control winding can be moved via the co-rotating inner conductor with a stationary, i. non-co-rotating terminal contact are connected.

Spool, coil core and insulator each have an opening for the

Implementation of the connection conductor. The openings extend in particular orthogonal to the common cylinder axis of bobbin, coil core and insulator. The openings are arranged one behind the other so that they form a continuous channel for the passage of the connection conductor.

As a result, the end of the control winding, which the actuating contact

is opposite, be connected via the connecting conductor with the inner conductor and the sliding contact.

For the two horizontal core elements in each case a Kernelementoffnung for carrying out the insulator and the inner conductor is provided from the transformer core. A Kernelementoffnung is preferably circular cylindrical. In particular, it has a diameter which corresponds to the inner diameter of the

Coil core corresponds. As a result, it is advantageously possible to arrange the insulator within the core element openings and the cavity of the spool core.

Because also each have a Kernelementoffnung of two themselves

is formed opposite segments of a circular hollow cylinder, whose Outer diameter preferably corresponds to the outer diameter of the spool core, circular hollow cylinder segments and spool core also have the same outer diameter and the same shell thickness. A magnetic field therefore passes through the circular cylinder segments and through the spool core. Due to the identical inner and outer diameter of the spool core and the

Circular cylinder segments are reduced leakage inductance and so the

Overall efficiency of the variable transformer improved.

The two cylinder ends of the insulator are each within a

Core element opening arranged, thus forming two bearings. Thereby, the insulator is rotatably arranged together with the inner conductor, the bobbin, the bobbin and the adjusting winding in the horizontal core elements.

The invention will be exemplified with reference to a drawing

described, with further advantageous details are shown in the figures of the drawing. Functionally identical parts are provided with the same reference numerals.

The figures of the drawing show in detail:

Figure 1 is a schematic view of the variable transformer 200;

Figure 2 is a schematic partial view of the movable core element in axial section; Figure 3a is a perspective view of the horizontal core elements 2a, 2b and the spool core 3;

Figure 3b is a perspective view of the horizontal core elements 2a, 2b and the bobbin 3 of Figure 3a in assembled

 Status; Figure 4 is an overall perspective view of the variable transformer 200;

and 5 shows a vertical section through the variable transformer 200nd

Figure 1 shows a schematic and simplified view of the variable transformer 200. This comprises a ferromagnetic transformer core 100 with a lower horizontal core element 2a and an upper horizontal core element 2b, which are connected by means of a vertical core element 1 and thus give a U-shape rotated by 90 degrees , The core elements 1, 2a, 2b are firmly connected together, i. immovable to each other. Furthermore, the transformer core 100 consists of movable elements, in particular a circular cylindrical

Spool core 3, in the space between the two horizontal

 Core elements 2a, 2b is rotatably arranged. All of these components consist of conventional dynamo sheets, i. from mutually isolated iron layers.

On the vertical core element 1, a primary winding 7 is wound, which forms a first circuit. The primary winding consists of insulated

Copper wire. As a result of the insulation, the copper wire is electrically insulated from the other windings and from the transformer core 1. If an alternating current is applied to the primary winding 7, then in the vertical 1 and the horizontal core elements 2a, 2b and in the rotatable spool core 3, a magnetic flux is generated, which changes its direction with the frequency of the alternating current. A second circuit is formed by a control winding 30 which is wound on the rotatable spool core 3. The control winding 30 is thus the secondary winding and the changing magnetic field of the transformer core 100 induces a voltage in the control winding 30.

In contrast to the insulated primary winding 7, the control winding 30 itself is not insulated and is exposed to the outside. The insulation of the control winding 30 of the spool core 3 is rather by a spool 5, not shown, (see Figure 2). The actuator winding 30 is single-layered and the windings are spaced so that there is no electrical contact between the individual windings. Since the windings are exposed, the control winding 30 can be contacted directly over its entire length. An electrical contact is made by means of a Stel Ikontaktes 22 which moves vertically up or down upon rotation of the control winding 30 and the spool core 3. As a control contact 22 is a

Carbon brush. The lower end of the control winding 30 ends blindly. The upper end of the actuator winding 30 is connected to a connection conductor 37 (not shown)

connected, guided by a vertically extending channel 32 in the spool core 3 and is electrically connected to an inner conductor 15. The inner conductor 15 is led out of the transformer core 100 through the spool core 3 and the upper horizontal core element 2b. In the area of the upper horizontal

Core element 2b, the inner conductor 15 is shown in dashed lines. The leading out of the upper horizontal core element 2b, the upper end of the inner conductor 15 is connected to a contact element 28. The contact element 28 consists of a slip ring 16 and a carbon brush 20. Upon rotation of the

Spool core 3, the inner conductor 15 rotates with the slip ring 16, since they are firmly connected. Slip ring 16 and carbon brush 20 thus form a

Sliding contact. The carbon brush 20 is connected to a connection element 24. The second connection element 24 is connected to the actuating contact 22. If a consumer (not shown) is connected to the two connection elements 24, then a second circuit is formed. By rotation of the spool core 3 and a synchronized therewith vertical movement of the actuating contact 22 along the

Actuator 30 is the effective length or the effective number of turns continuously variable. Because the ratio of the number of turns of the two

Windings 7, 30 directly proportional to the induced in the control winding 30

Voltage is, thus, the voltage of the variable transformer 200 can be adjusted continuously. Between the spool core 3 and the horizontal core elements 2a, 2b there is an air gap 31 in each case. This is shown very broadly in FIG. 1 for reasons of clarity. In fact, the air gap 31 should be as narrow as possible in order to minimize the attenuation of the magnetic flux between the horizontal core elements 2a, 2b and the spool core 3. FIG. 2 shows a partial view of the movable core element in axial section. This comprises the bobbin 5, the coil core 3 and an insulator 11. The three elements are each formed as a hollow cylinder, wherein the insulator 1 1 are arranged in the bobbin 3 and both in turn in the bobbin 5. The parts and their dimensions and distances from each other are for the sake of

Illustrated only schematically and do not reflect the real size relationships. The bobbin 5 is made of a dielectric plastic, namely of polyethylene. It has a circumferential recess 33 which serves as a guide and embedding for the control winding 30. The control winding 30 is thus held in position. The dielectric bobbin 5 also isolates the control winding 30 from the ferromagnetic coil core 3. The ferromagnetic coil core 3 amplifies the magnetic field generated by the control winding 30. In its opening 23, a dielectric insulator 1 1 is arranged for an electrical inner conductor 15. The control winding 30 is connected by means of a horizontally extending connecting conductor 37 with the inner conductor 15. The connecting conductor 37 is guided for this purpose by a horizontally extending channel 32 of the bobbin 5, the bobbin 3 and the insulator 1 1 in the axial opening 14 of the insulator 1 1, where it is electrically connected to the inner conductor 15. The inner conductor 15 is then guided with the insulator 1 1 through the upper horizontal core element 2b and electrically connected to the slip ring 16. The three hollow cylinder described are firmly connected to each other in the transformer 200, that is not mutually displaceable or rotatable. If the control winding 30 is rotated, then rotate together with the control winding 30 and the outer dielectric bobbin 5, the coil core 3, the insulator 1 1 and the inner conductor 15 and the associated slip ring 16 (not shown, see Figure 1) to their common central longitudinal axis.

In order to increase the efficiency of the variable transformer 200, the inner conductor 15 consists of a strand of insulated individual wires wrapped with an insulating dielectric. This prevents that a so-called skin effect occurs, which would increase the impedance of the inner conductor 15. FIG. 3a shows a schematic, perspective view of the lower one

horizontal core element 2a, the upper core element 2b and the spool core 3. The coil core 3 is shown as "floating" between the two core elements 2a, 2b, ie, for reasons of clarity, the distances between the coil core 3 and the horizontal core elements 2a, 2b, ie the air gaps 31, are shown considerably wider Core elements 2a, 2b are identical components whose longitudinal axes are parallel to one another and are each connected at one end to a vertical core element 1 (not shown), thereby forming the shape of a U rotated by 90 degrees have a cuboid basic shape in the area of the rotatable

Spool core 3, however, each horizontal core element 2a, 2b, a thickening or two bulges in the form of a front 36 'and a rear

Circular cylinder segment 36 ', 36 "are arranged opposite each other and have a common cylindrical

Core element opening 35 on. The lower or upper horizontal core element 2a, 2b is therefore also referred to below as "hollow circle cylinder", on the lateral surface of which two cuboids are formed.

The rotatable spool core 3 is also a circular cylinder with a cylindrical cavity forming an opening 23, ie a hollow cylinder. It can be seen from FIG. 3a that the diameter of the coil core opening 23 corresponds to the diameter of the core element opening 35, wherein both openings 23, 35 have a common central axis (not shown). It can also be seen that the outer diameter of the spool core 3 the

The outer diameter of the hollow cylindrical cylinder formed by the circular cylinder segments 36 ', 36 "corresponds

Circular cylinder segments 36 ', 36 "also have the same sheath thickness, so the magnetic field generated by the coil 7 extends from the vertical one

Core element 1 through the upper horizontal core element 2b, then through the upper circular cylinder segments 36 ', 36 ", then through the spool core 3 and the circular cylinder segments 36', 36" of the lower horizontal core element 2a, or in the reverse direction. Due to the identical inner and outer diameter of the spool core 3 and the circular cylinder segments 36 ', 36 "are stray inductances reduced and so the overall efficiency of the variable transformer improved.

FIG. 3b shows a perspective view of the horizontal core elements 2a, 2b and of the spool core 3 according to FIG. 3a in the assembled state. The elements are shown as they are also arranged in the variable transformer 200. It is shown that the two air gaps 31 are very narrow. In addition to FIG. 3a, the dielectric insulator 11 is shown. This is in the openings 23, 35 (not visible, see Figure 3a) of the spool core 3 and the

Circular cylinder segments 36 ', 36 ".The cylindrical openings 35 in the thickening formed by the two circular cylinder segments 36', 36" each form an upper and lower bearing with the corresponding one

Lateral surface portion of the insulator 1 1. As a result, the insulator 1 1 is rotatably mounted.

The upper and lower ends of the insulator 1 1 protrude from the

Core element openings 35 out. At the lower end (not shown), it is coupled to a gear 26 (not shown). At its upper end of the (not shown) slip ring 16 is arranged, which also rotates.

Figure 4 shows an overall perspective view of the variable transformer 200 with the horizontal core elements 2a, 2b and the vertical core element 1, around which the primary winding 7 is wound with an insulation 6. At the two horizontal core elements 2 a, 2 b, a total of four reinforcing elements 12 made of non-magnetizable material are fastened with insulating washers 27. These stabilize the mechanical structure. The two horizontal core elements 2a, 2b are identical components whose longitudinal axes are parallel to each other and which are each connected at one end to the vertical core element 1, whereby the three core elements form the shape of a U rotated by 90 degrees. Two opposite bulges have the form of

Circular cylinder segments 36 ', 36 "Furthermore, a core element opening 35 is provided for both horizontal core elements 2a, 2b, through which the insulator 1 1 is guided with the inner conductor 15. On the upper end of the insulator 1 1 sits the slip ring 16, wherein he surrounds the inner conductor 15 contacting Slip ring 16 forms with the carbon brush 20 a sliding contact, which is protected by a sliding contact housing 17 with a housing flap 19.

Since the slip ring 16 and the carbon brush 20 is disposed outside of the transformer core 100, no eddy currents occur in it and the efficiency of the variable transformer is thereby significantly improved.

The sliding contact housing 17 has an opening 34 for the terminal contact 24, which is connected to the carbon brush 20. Between the two thickenings 36 ', 36 "of the two lower and upper horizontal core elements 2a, 2b, the control winding 30 is arranged on the rotatable bobbin 5. The insulator 1 1, which is rotatable with the bobbin 5, has a toothed wheel 26 on its lower side The gear wheel 26 engages a smaller gear 25 to form a gear which drives a threaded spindle 10. A pin 13 (not visible) arranged in a control housing 8 engages the recess of the thread and prevents rotation In this case, the (non-visible) actuating contact 22 moves vertically together with its actuating contact housing 8, the steep contact housing flap 21 and the pin 13. The two rear reinforcing elements 12 serve as a guide for the actuating contact housing 8 At the opposite ends of the primary winding from the horizontal

Core elements 2 a, 2 b are each a threaded spindle base 4 attached, which as

Holder and bearing for the threaded spindle 10 serve. The threaded spindle bases 4 consist of the same non-magnetic and non-magnetizable

Material as the reinforcing elements 12. The thread of the threaded spindle 10 and the gear formed from the two gears 25, 26 are so

matched that with a rotation of the actuating contact 22 is always exactly on the control winding 30 and contacted them. As a result, a precise stepless adjustment of the variable transformer 200 is possible.

Figure 5 shows a vertical section through the variable transformer 200. This comprises the primary winding 7, which is wound around the vertical core element 1, the lower horizontal core element 2a and the upper horizontal core element 2b. Between the two horizontal core elements 2a, 2b is the control winding 30 arranged in the recesses 33 of the bobbin 5. In the bobbin 5 is coil core 3 with the insulator 1 first Inside the insulator 11, the inner conductor 15 extends. The inner conductor 15 is electrically connected to one end of the control winding 30 by means of a connecting conductor 37. Of the

Connecting conductor 37 is guided by the bobbin 5, the bobbin 3 and the insulator 1 1. The inner conductor 15 and the insulator 11 pierce the upper 2b and the lower horizontal core element 2a. On the upper side of the insulator 1 1, the slip ring 16 is fixed, which contacts the inner conductor 15. On the

Slip ring 16 presses a carbon brush 20, which is pressed by a spring 18 against the slip ring 16. In case of wear of the carbon brush 20, this automatically replaces.

At the bottom of the insulator 1 1, the large gear 26 is fixed, which drives the threaded spindle 10 on a common rotation of control winding 30, bobbin 5, spool core 3, insulator 1 1, inner conductor 15 and slip ring 16 via the small gear 25. The pin 13 engages in the recesses of the thread of the threaded spindle 10 a. As a result, the pin 13 and with it moves in a rotation depending on the direction of rotation upwards or downwards, wherein he takes the actuating contact 22. The actuating contact 22 formed by a carbon brush is pressed against the control winding 30 by a spring (not shown). The illustrated variable transformer 200 has a very high efficiency and can be used for power in the range of 100 to 250 megavolt ampere. It is therefore particularly suitable for power plants, where the voltage must be continuously adapted to different network conditions.

List of Reference Numerals. Vertical core element

a. Lower horizontal core element b. Upper horizontal core element. Plunger

, Screw base

, bobbins

, insulation

, primary

, Alternate contact housing

, Opening of the bobbin

0. threaded spindle

1 . insulator

2. reinforcing element

3rd pin

4. Isolator opening

5. Inner conductor

6. slip ring

7. Sliding contact housing

8. spring

9. Sliding contact housing flap

0. carbon brush

1 . Contact steep housing flap

2. Stel Ikontakt

3. Spool core opening

4. Connection element

5. Small gear

6. Big gear

7. Insulating washer

8. Contact element

0. adjusting winding

1 . air gap

2nd channel for connection conductor

3rd recess

4. housing opening

5. core element opening

6 '. Front circular cylinder segment6 "

7. Connecting conductor

00. transformer core

00. variable transformer

Claims

claims 1 . Stepless variable transformer having a transformer core (100), a primary winding (7), a single-layer contactable control winding (30), a control contact (22) adjustable along the control winding (30) and a contact element (28) connected to one end of the control winding (30) ), characterized in that the contact element (28) is arranged outside of the transformer core (100). 2. Stepless variable transformer according to claim 1, characterized in that the control winding (30) forms a coil which is rotatable about its longitudinal axis. 3. Stepless variable transformer according to claim 1 or claim 2, characterized in that for the control winding (30) a, in particular ferromagnetic, coil core (3) is provided. 4. Stepless variable transformer according to one of the preceding claims, characterized in that the ferromagnetic transformer core (100) has a lower horizontal core element (2a) and an upper  horizontal core element (2b) which is connected by means of a vertical core element (1), so that approximately results in a U-shape rotated by 90 degrees and the bobbin (3) with the control winding (30) in the space between the horizontal core elements (2a, 2b) is arranged, wherein the core elements (1, 2a, 2b, 3) are preferably made of dynamo sheets. 5. Stepless variable transformer according to one of the preceding claims, characterized in that between the control winding (30) and  Spool core (3) a bobbin (5) of dielectric material,  in particular of polyethylene, is provided, which has a circumferential recess (33) as a guide for the control winding (30). 6. Stepless variable transformer according to one of the preceding claims, characterized in that the control winding (30) via a Connecting conductor (37) connected to an electrical inner conductor (15) is, which is connected to the outside of the transformer core (100) arranged contact element (28). 7. Stepless variable transformer according to one of the preceding claims, characterized in that the inner conductor (15) consists of a strand of insulated, parallel-connected individual conductors, in particular of copper, and is surrounded by an insulator (1 1). 8. Stepless variable transformer according to one of the preceding claims, characterized in that bobbin (5), coil core (3) and insulator (1 1) are each formed as a circular hollow cylinder, wherein the coil core (3) in the cavity of the bobbin (5), the insulator (1 1) in the cavity of the coil core (3) and the inner conductor (15) in the cavity of the insulator (1 1) is arranged. 9. Stepless variable transformer according to one of the preceding claims, characterized in that the control winding (30), bobbin (5), coil core (3), insulator (1 1) and inner conductor (15) fixedly connected to each other, rotatable together and preferably via a transmission (25, 26) are coupled to a threaded spindle (10) for driving the actuating contact (22) in order to effect a rotation of a synchronized vertical movement of the actuating contact (22) along the control winding (30). 10. Stepless variable transformer according to one of the preceding claims, characterized in that the contact element (28) as a sliding contact, in particular as a slip ring (16) with a brush (20) is formed. 1 1. Stepless variable transformer according to one of the preceding claims, characterized in that bobbin (5), coil core (3), insulator (1 1) each have one, in particular orthogonal to their cylinder axes, opening, wherein the openings are arranged one behind the other, that they a continuous channel (32) for the Forming the connection conductor (37) form. 12, stepless Stelltransfornnator according to any one of the preceding claims, characterized in that for the horizontal core elements (2a, 2b) each have a core element opening (35) for carrying out the insulator (1 1) and the inner conductor (15) from the transformer core (100) is, wherein the core element opening (35) is preferably circular cylindrical and in particular has a diameter corresponding to the inner diameter of the spool core (3). 13. Stepless variable transformer according to one of the preceding claims, characterized in that in each case a core element opening (35) of two opposite segments of a circular hollow cylinder (36 ', 36 ") is formed, whose outer diameter is preferably the  Outer diameter of the spool core (3) corresponds. 14. Stepless variable transformer according to one of the preceding claims, characterized in that the two cylinder ends of the insulator (1 1) each within a core element opening (35) are arranged to form two bearings, through which the insulator (1 1) together with the  Inner conductor (15), the spool core (3), the bobbin (5) and the control winding (30) is rotatable.