EP4111478A1

EP4111478A1 - Insulation end ring for transformer

Info

Publication number: EP4111478A1
Application number: EP20920995.6A
Authority: EP
Inventors: Chengqing ZHANG; Lili Han
Original assignee: Hitachi Energy Switzerland AG
Current assignee: Hitachi Energy Ltd
Priority date: 2020-02-28
Filing date: 2020-02-28
Publication date: 2023-01-04
Also published as: CN115066733A; WO2021168788A1; EP4111478A4

Abstract

An insulation end ring and a transformer. The insulation end ring (100) comprises a ring body (101) adapted to be arranged between two coils (202) helically wound in a layer around a core (203), wherein circumferential edges (1013) of the ring body (101) are in helical shapes and allow the coils (202) to be synchronously wound along a respective one of the circumferential edges (1013) to form helical shapes of the adjacent coils (202). By both of the circumferential edges (1013) of the ring body (101) being in helical shapes, the coils (202) of the split-coil transformer sharing one common core (203) can be synchronously wound along the circumferential edges (1013), respectively. In this way, the efficiency for winding the coils (202) is significantly improved. Furthermore, the spacer plate is no longer needed. As a result, the total height of the split-coil winding is reduced, thereby reducing the weight and the volume of the transformer.

Description

INSULATION END RING FOR TRANSFORMER

FIELD

Embodiments of the present disclosure generally relate to a transformer, and more specifically, to an insulation end ring for the transformer.

BACKGROUND

A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to one or more circuits. A varying current in any one coil of the transformer produces a varying magnetic flux, which, in turn, induces a varying electromotive force across any other coils wound around the same core. Electrical energy can be transferred between the (possibly many) coils, without a metallic connection between two circuits.
Split-coil transformers are usually manufactured from multiple split coils in which the high voltage coils are in parallel. Typically, in a split-coil transformer, two or more coils axially share one common core. In the event of a short circuit, there is considerable distortion of the leakage field, which produces high axial short circuit forces. The split-coil arrangement thus requires special short circuit design considerations.
Additionally, in order to allow the axial forces to be evenly applied to the coils sharing one common core, in conventional split-coil transformers, insulation end rings are usually arranged at ends of each layer of the two coils. Further, due to the split-coil arrangement, a spacer plate is also arranged between the insulation end rings to improve the insulation performance. That is, there are two end rings and a spacer plate arranged between two coils sharing one common core. As a result, the coils have to be wound one by one, which results in a reduced winding efficiency. Furthermore, the spacer plate increases the size of the core and even the volume of the tank for receiving the windings.
SUMMARY
Embodiments of the present disclosure provide an insulation end ring and a transformer using the insulation end ring to at least in part solve the above and other potential problems.
In a first aspect, an insulation end ring is provided. The insulation ring end ring comprises a ring body adapted to be arranged between two coils helically wound in a layer around a core, wherein circumferential edges of the ring body are in helical shapes and allow the coils to be synchronously wound along a respective one of the circumferential edges to form helical shapes of the adjacent coils.
By providing both of the circumferential edges of the ring body in helical shapes, the coils of the split-coil transformer sharing one common core can be synchronously wound along the circumferential edges, respectively. In this way, the efficiency of winding the coils is significantly improved. Furthermore, the spacer plate is no longer needed. As a result, the total height of the core is reduced, thereby reducing the weight and the volume of the transformer.
In some embodiments, a first axial edge and a second axial edge of the ring body extend between the circumferential edges and are adjacent to each other to form an axial slit of the ring body. With this arrangement, the insulation end ring can be easily arranged on the core.
In some embodiments, the first axial edge and the second axial edge are parallel to each other. This arrangement makes the pressure on the coil more even.
In some embodiments, the circumferential edges are symmetrical with respect to a plane radially extending and passing through a midpoint of the first axial edge or the second axial edge. In this way, the symmetrical arrangement of the coils can be achieved.
In some embodiments, a length of the first axial edge is longer than a length of the second axial edge, and each of the circumferential edges forms an inclined straight line when the ring body is unrolled. This arrangement facilitates the manufacturing of the insulation end ring.
In some embodiments, a radial thickness of the ring body is uniform and substantially the same as a thickness of each layer of the coils. As a result, each of layers wound on the core can be more even to ensure a more stable mechanical strength of the winding.
In some embodiments, a diameter of the ring body is the same as a diameter of each layer of coils. This arrangement facilitates the arrangement of the insulation end ring on each layer.
In some embodiments, the ring body is formed by cutting a cylindrical member along the circumferential edges. In this way, the insulation end ring can be manufactured easily.
In some embodiments, the ring body is formed by molding or winding a plate about an axis parallel to any of the first axial edge or the second axial edge.
In some embodiments, the ring body is elastically deformable to allow it to be arranged to surround the core. This arrangement facilitates the arrangement of the insulation end ring on each layer.
In a second aspect, a transformer comprising an insulation end ring as mentioned in the above first aspect is provided
It is to be understood that the Summary is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives, features and advantages of the present disclosure will become more apparent through more detailed depiction of example embodiments of the present disclosure in conjunction with the accompanying drawings, wherein in the example embodiments of the present disclosure, same reference numerals usually represent same components.
FIG. 1 shows a schematic diagram of an insulation end ring arranged between two coils according to embodiments of the present disclosure;
FIG. 2 shows a perspective view of an insulation end ring according to embodiments of the present disclosure;
FIG. 3 shows a side view of an insulation end ring according to embodiments of the present disclosure;
FIG. 4 shows a top view of an insulation end ring according to embodiments of the present disclosure; and
FIG. 5 shows a side view of an insulation end ring according to embodiments of the present disclosure.
Throughout the drawings, the same or similar reference symbols are used to indicate the same or similar elements.

DETAILED DESCRIPTION

The present disclosure will now be discussed with reference to several example embodiments. It is to be understood these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the subject matter.
As used herein, the term “comprises” and its variants are to be read as open terms that mean “comprises, but is not limited to. ” The term “based on” is to be read as “based at least in part on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The terms “first, ” “second, ” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be comprised below. A definition of a term is consistent throughout the description unless the context clearly indicates otherwise.
As mentioned above, a split-coil type transformer, which is usually manufactured from multiple split coils, is widely used to divide large blocks of transmitted power among low voltage buses and thus eliminate the concentration of energy. Typically, in the split-coil transformer, two or more coils axially share one common core. For example, in some conventional solutions, two coils are wound around a core layer by layer to form a winding. “Winding” refers to a component or element having a core and a group of coils wound thereon. That is, the winding is a product in which a group of coils have been wound on the core.
Windings are used as components of circuits and to provide the magnetic field for motors, transformers, and generators, and in the manufacture of loudspeakers and microphones. The shape and dimensions of a winding are designed to fulfill a particular purpose. Coil winding can be structured into several groups based upon the type and geometry of the wound coil.
Helical winding is typically used in a transformer. For split-coil helical winding, separate coils are typically wound helically around the common core layer by layer, thereby forming helical edges on both axial ends of each coil in each layer. To transform the helical edges of each coil into flat circle rings, in conventional solutions, insulation end rings are arranged at the helical edges of each coil. That is, in conventional solutions, there are two insulation rings between the two coils sharing one common core. Furthermore, between the two insulation rings in each layer, a spacer plate is arranged.
Due to the presence of multiple components between the coils axially arranged on the same core, the split cores should be wound successively to ensure accurate positions of the split coils on the same core that minimizes as much as possible axial short circuit forces applied to the coils. That is, one of the coils in each layer is wound first, and then another is wound after the first wound coil is finished and so on, which results in a low production efficiency. Nevertheless, multiple components arranged between the split coils makes it more difficult to achieve accurate positions of the split coils.
Furthermore, the presence of the two insulation end rings and the spacer plate between the split coils causes a relatively large axial scale of each core, which requires a large volume of a tank for receiving the split windings containing a large amount of cooling medium in the tank. This arrangement necessarily leads to a large volume and weight of the transformer.
In order to at least in part address the above and other potential problems, embodiments of the present disclosure provide an insulation end ring for the windings of a transformer. FIG. 1 shows a schematic diagram of an insulation end ring arranged between two coils according to embodiments of the present disclosure.
As shown, the insulation ring 100 according to embodiments of the present disclosure generally comprises a ring body 101. The ring body 101 can be arranged between two coils 202 which are helically wound in a layer around a core 203. As mentioned above, there may be multiple layers of coils around the core 203 to form a winding of a transformer. In each layer, at least two coils are wound to form helical shapes.
Contrary to the convention solutions, the ring body 101 has two circumferential edges which are both in helical shapes. As a result, in each layer of the coils, only one insulation end ring 100 is needed without requirement for an extra insulation end ring and a spacer plate. Accordingly, the coils 202 in each layer can be synchronously wound along a respective one of the circumferential edges 1013 to form helical shapes of the coils 202. In this way, the production efficiency of the transformer can be significantly improved.
Furthermore, without the spacer plate, a total height of the core can be reduced, which also leads to reductions in the volume of the winding and the tank for arranging the windings. Furthermore, cooling medium required in the tank is reduced, resulting in a weight reduction of the transformer. Moreover, a single component, i.e., the insulation end ring 100, rather than multiple separate components between the coils in each layer can enhance the mechanical strength of the winding.
In some embodiments, a first axial edge 1011 and a second axial edge 1012 of the ring body 101 which extend between the circumferential edges 1013 are adjacent to each other to form an axial slit, as shown in FIGS. 1 and 2. The first and second axial edges 1011, 1012 can facilitate the arrangement of the insulation end ring 100 around the core or around the previously wound layer.
In some embodiments, the ring body 101 may be elastically deformable. In this way, when assembling the insulation end ring 100 around the core or the previously wound coils, the user can deform the insulation end ring 100 via the axial slit. The deformed insulation end ring 100 can also facilitate holding of the insulation end ring 100 on the core 203. In some embodiments, the insulating end ring may be made of a suitable elastic insulation material.
As shown in FIGS. 2 and 3, in some embodiments, the first and second axial edges 1011, 1012 have different lengths. For example, the length of the first axial edges 1011 is longer than a length of the second axial edge 1012. In this way, when the ring body 101 is unrolled into a plane, each of the circumferential edges 1013 forms an inclined straight line. That is, the ring body 101 is of a trapezoidal shape when fully unrolled.
This arrangement may facilitate the manufacture of insulated end rings. For example, in some embodiments, the ring body 101 may be formed by winding a trapezoidal shape plate about its long edge or short edge. After the ring body 101 is formed in a ring shape, as shown in FIG. 4, the long and short edges of the trapezoidal shape plate are formed as the first and second axial edges 1011, 1012, respectively. Accordingly, the inclined edges of the trapezoidal shape plate are formed as the circumferential edges 1013.
It is to be understood that the above embodiments where the ring body 101 is formed by rolling a trapezoidal shape plate are merely for illustrative purposes. Any other suitable means or methods are possible as well. For example, in some alternative embodiments, the ring body 101 may also be formed by cutting a cylindrical blank along the circumferential edges 1013. This approach can further facilitate the manufacturing of the insulation end ring 100 and thereby to improve the production efficiency. In some further alternative embodiments, the ring body 101 may also be formed by molding or the like.
As shown in FIG. 5, in some embodiments, the circumferential edges 1013 are symmetrical with respect to a plane which radially extends and passes through a midpoint of the first or second axial edge 1011, 1012. It is appreciated that in a case where the ring body 101 is formed by rolling a trapezoidal shape plate, the trapezoidal shape plate is of an isosceles trapezoid.
Referring back to FIG. 4, in some embodiments, a radial thickness of the ring body 101 is uniform and substantially the same as a thickness of each layer of the coils 202. As a result, each of the layers wound on the core can be more even to ensure a more stable mechanical strength of the winding.
Furthermore, in some embodiments, a diameter of the ring body 101 is the same as a diameter of each layer of coils 202 to facilitate the arrangement of the insulation end ring 100 around the core or the previous wound coils. In this way, the accurate positions of coils can be ensured.
In can be seen from the above that according to embodiments of the present disclosure, by providing both of the circumferential edges 1013 of the ring body 101 in helical shapes, the coils 202 sharing one common core 203 can be synchronously wound along the circumferential edges 1013, respectively. In this way, the efficiency of winding the coils 202 is significantly improved. Furthermore, the total height of the split-coil winding is reduced, thereby reducing the weight and the volume of the transformer.
Embodiments of the present disclosure further provide a transformer comprising insulation end rings 100 as mentioned above. With the insulation end ring 100, the transformer can be made more compact and lightweight.
It should be appreciated that the above detailed embodiments of the present disclosure are only to exemplify or explain principles of the present disclosure and not to limit the present disclosure. Therefore, any modifications, equivalent alternatives and improvement, etc. without departing from the spirit and scope of the present disclosure shall be comprised in the scope of protection of the present disclosure. Meanwhile, appended claims of the present disclosure aim to cover all the variations and modifications falling under the scope and boundary of the claims or equivalents of the scope and boundary.

Claims

An insulation end ring (100) , comprising:

a ring body (101) adapted to be arranged between two coils (202) helically wound in a layer around a core (203) , wherein circumferential edges (1013) of the ring body (101) are in helical shapes and allow the coils (202) to be synchronously wound along a respective one of the circumferential edges (1013) to form helical shapes of the adjacent coils (202) .
The insulation end ring of claim 1, wherein a first axial edge (1011) and a second axial edge (1012) of the ring body (101) extend between the circumferential edges (1013) and are adjacent to each other to form an axial slit of the ring body (101) .
The insulation end ring of claim 2, wherein the first axial edge (1011) and the second axial edge (1012) are parallel to each other.
The insulation end ring of claim 2, wherein the circumferential edges (1013) are symmetrical with respect to a plane radially extending and passing through a midpoint of the first axial edge (1011) or the second axial edge (1012) .
The insulation end ring of claim 2, wherein a length of the first axial edge (1011) is longer than a length of the second axial edge (1012) , and

each of the circumferential edges (1013) forms an inclined straight line when the ring body (101) is unrolled.
The insulation end ring of claim 1, wherein a radial thickness of the ring body (101) is uniform and substantially the same as a thickness of each layer of the coils (202) .
The insulation end ring of claim 1, wherein a diameter of the ring body (101) is the same as a diameter of each layer of coils (202) .
The insulation end ring of claim 1, wherein the ring body (101) is formed by cutting a cylindrical member along the circumferential edges (1013) .
The insulation end ring of claim 1, wherein the ring body (101) is formed by molding or winding a plate about an axis parallel to any of the first axial edge (1011) or the second axial edge (1012) .
The insulation end ring of claim 1, wherein the ring body (101) is elastically deformable to allow to be arranged to surround the core (203) .
A transformer comprising an insulation end ring of any of claims 1-10.