EP2549495A1 - Dry type transformer - Google Patents

Abstract

The transformer has transformer core, radially inner winding segment (34) and radially outer winding segment (32) wound around common winding axis. The hollow cylindrical cooling ducts (36,38) are formed between winding segments. The spacer elements (40,42) are arranged such that cooling ducts allows coolant passage in axial direction. The spacer elements are formed along duct radial circumference over axial length, such that proportionate weight of horizontal transformer is borne on contact surface (44) of winding segment (32) without causing deformation to cooling ducts.

Description

The invention relates to a dry-type transformer for mobile applications, comprising a transformer core and at least one radially inner first and one radially outer second wound around a common winding axis and penetrated by the transformer core hollow cylindrical winding segment, which are nested and radially spaced from each other, so that between a hollow cylindrical Cooling channel is pronounced, wherein spacer elements are provided for spacing, which are arranged such that the cooling channel can be flowed through in the axial direction of a coolant.

It is well known that appropriate line-based utility networks are available for the transmission of electrical energy. Depending on the electrical power to be transmitted, these have a nominal voltage of, for example, 380 kV, 110 kV or even 10 kV, with typically a mains frequency of 50 or 60 Hz being used. A supply network for the supply of stationary loads is typically 3-phase, so there is a system with three supply lines available, in which the current and voltage in a symmetrical state at a phase shift of 120 ° to each other in terms of amount are equal.

Energy supply systems for mobile consumers, such as railways or trams are typically constructed in a single phase, ie the supply takes place via a single supply line, wherein the return line then takes place via the metallic rail. In trolleybuses two supply lines are usually provided due to the non-existent and usable as a return rail rail. Typically, the network frequency in such applications, at least in Europe 16 2/3 Hertz, in some cases, such as S-Bahn also isolated DC voltage is used.

To transform the typical AC supply voltage of 10kV to 15kV mobile transformers are provided, which are then integrated, for example, in the underfloor area of a passenger train.

These have due to the underfloor arrangement only one in particular in terms of height very limited space available and are usually designed as oil transformers. The oil serves on the one hand as a coolant to dissipate the heat loss generated during operation and as an insulating means by which smaller insulation distances and thus a compact design can be realized.

The disadvantage here, however, is that such a transformer for mechanical reasons can usually be arranged only upright, but this is contrary to the flat space in the underfloor area. In addition, for safety reasons, oil should be avoided as a combustible medium in a means of transport if possible. In this case, in particular eliminates the cooling effect of the oil.

Based on this prior art, it is an object of the invention to provide a flexible as possible to arrange dry transformer for mobile applications.

This object is achieved by a dry-type transformer of the type mentioned at the outset. This is characterized in that the spacer elements are so shaped and arranged along the radial circumference of the cooling channel over its axial length that the proportional weight of the horizontal transformer lies against at least one contact surface of the at least one second winding segment can be removed without a deformation of the cooling or the scattering channel formed by this occurs.

By eliminating the oil as a coolant, which dissipates the heat loss generated during operation, for example, to a heat exchanger, an alternative cooling system is provided, which works without oil but preferably with air. Due to the lower heat capacity of air, a significantly enlarged contact surface of the transformer winding to the cooling medium is therefore provided according to the invention. Furthermore, an increased coolant throughput, for example by means of a blower, is advantageous.

This is achieved in particular by the cooling channels which are provided between the nested hollow-cylindrical winding segments. These serve on the one hand to influence the short-circuit impedance of the dry-type transformer according to the invention, and are therefore also to be regarded as a stray channel insofar as they are arranged between two galvanically separated winding segments. On the other hand, these serve to cool the transformer winding from the inside. In accordance with the invention, provision is made for a coolant, in particular air, to be forced to flow through these cooling channels. Air has the advantage that the heated air can be discharged directly to the environment without an additional heat exchanger. According to the invention, additional cooling channels are optionally provided to increase the cooling surface, for example, between a plurality of series-connected winding segments, which form a lower or higher voltage winding. As a result, however, the required space requirement of the dry-type transformer according to the invention is increased compared to a comparable oil transformer.

Therefore, it is provided according to the invention to arrange the transformer lying, so that the winding axis of the windings thus extends in a horizontal plane. As a result, a particularly flat and more planar construction of the transformer is achieved, which accommodates the available flat but rather large space in the underfloor area.

The spacing of the hollow-cylindrical winding segments is provided by spacer elements of insulating material, through which a support is provided in at least predominantly radial direction to the winding axis. The installation of such a dry-type transformer according to the prior art is vertical. This has for one cooling reasons, namely that then along the winding axis extending cooling channels are then operated by natural cooling by ambient air flows from bottom to top through the cooling channels. On the other hand, this is also mechanical. In a vertical arrangement, the transformer is namely on the bottom of its transformer core, so its entire weight, for example, 500kg to 1000kg, can be removed directly on the support surface of the transformer core on the floor space. The arranged on the legs of the transformer core windings are thus aligned vertically and thus exposed predominantly weight forces in the direction of the winding axis. A force stress in the winding of a direction radially to the winding axis does not take place in a vertical orientation of the transformer.

Due to the typically non-existent or only insignificant force stress in the radial direction, the support elements of the cooling channels of a dry-type transformer of the prior art are also correspondingly not designed for such a radial force load. Nevertheless, it is provided according to the invention, the dry-type transformer lying on corresponding bearing surfaces of its windings can be arranged or at least storable. Even if a dry transformer in the underfloor area is mainly attached to the sides of its transformer core, so that actually its weight would not be removed through the windings, so its transformer core but with a length of for example 2m is so long that due to gravity, a deflection of the same takes place. Thus, even in this case, the winding according to the invention for receiving increased radial forces to be trained to counteract bending.

In order to realize the lying arrangement according to the invention of the dry-type transformer on corresponding bearing surfaces of the outer surfaces of the windings, the respective windings are to be trained accordingly also for receiving radial force stresses. According to the invention, therefore, it is provided that the arrangement of spacer elements be compacted accordingly in critical areas for a specific arrangement position of the transformer so that the maximum compressive stress per base area of a spacer element is not exceeded, even in the horizontal position of the dry transformer. Alternative to an insulating material, such as a glass fiber reinforced composite or pressboard, depending on the voltage conditions over the cooling channel and the use of a metal for a spacer conceivable, for example, a solid aluminum profile, insofar as the cooling channel is located between multiple segments of a low-voltage winding, for example, 400V. In this case, no isolation capability of the spacer is required due to the low voltage stress, but this is already taken over by the usual insulation of the winding conductor. A typical size of a transformer according to the invention with a two leg core, for example, has a length of, 1.5m - 2.5m, a height of 0.75m and a width of 1.5m.

The dry-type transformer according to the invention advantageously avoids the use of oil and nevertheless has suitable cooling possibilities. Furthermore, it is designed by its horizontal arrangement in flat construction, so that it can be easily integrated into the underfloor area of a locomotive or a wagon. By a selective reinforcement or compression of the spacer elements in the cooling channels, a corresponding stabilization of the winding (s) is carried out for a horizontal position of the transformer to remove the entire weight of the transformer down.

According to a further embodiment of the dry-type transformer according to the invention, the at least one second winding segment has exactly one respective preferred contact surface, via which only the proportionate weight of the horizontal transformer can be removed, without a deformation of the cooling channels. The dry-type transformer then has a specific lying preferred position. Thus, the spacers are only for the preferred position to strengthen or compact, so that the cost of the reinforcement is reduced to a minimum.

According to a further variant of the invention, therefore, the spacer elements are arranged compressed in the radial direction to the respective bearing surface, so that there is an increased radial compressive strength in the corresponding areas of the cooling channel. It is basically given material of the spacer elements, the possibility of this in the appropriate areas either in a smaller distance from each other, so compressed, to order, or even to increase the width or contact surfaces of the spacer elements accordingly.

According to a further embodiment of the invention, the spacer elements are strip-like or channel-like and preferably extend along the winding axis. As a result, the hollow cylindrical cooling channel is subdivided into a plurality of fluidically favorable running in the axial direction of the cooling channels. The cooling effect is thus improved and homogenized in an advantageous manner.

According to a further embodiment of the invention, the spacer elements are pronounced as selective support elements. This offers on the one hand manufacturing advantages, for example, in accordance with diagonal to the axial direction staggered arrangement of the selective support elements also improved cooling effect is achieved. A punctiform support element has, for example, a circular floor plan, for example with a diameter of 4 cm, and a height of also 4 cm, depending on the desired shape of the scattering or the cooling channel.

According to a further embodiment of the dry-type transformer according to the invention, a respective hollow-cylindrical third winding segment interleaved between the respective first and second winding segments is provided, wherein in each case a cooling channel is provided between the respective winding segments. Preferably, the at least one radially inner first and the at least one radially outer second winding segment is provided for undervoltage and the at least one radially middle third winding segment for high voltage. Due to the atypical arrangement of the high-voltage winding, so for example with a rated voltage of 15kV, between two low-voltage windings, for example, with a rated voltage of 0.4kV, the short-circuit impedance of the transformer is advantageously increased, which then leads to reduced short-circuit currents in case of failure. The radially inner winding is provided for example for the supply of a train heating, while the radially outer winding is then provided for the supply of the drive.

According to a preferred embodiment of the invention, the transformer core has exactly two legs around which in each case at least one first and one second winding segment are arranged. The Zweischkelausführung is particularly in consideration of the single-phase of a traction power supply network advantage. The division of the respective lower and upper voltage windings on the two legs leads to an increased utilization of the available space and thus to a very compact design of the transformer according to the invention.

According to a preferred embodiment variant of the dry-type transformer, the latter is arranged in a housing enclosing it, which has an inlet opening and an outlet opening, wherein air baffles are provided within the housing, which are arranged such that coolant entering through the inlet opening along the respective nested winding segments is serpentine-like through the housing or the cooling channels or scattering channels formed in them is guided to the outlet opening. On the one hand, the housing offers mechanical protection of the transformer, which is particularly advantageous in the case of the arrangement in the underfloor area. The guidance of the cooling air longitudinally through air baffles of defined channels preferably through the cooling or stray channels improves the cooling effect. Due to the serpentine-like guidance of the cooling air along respective winding segments, in particular for the variant with two nested winding segments, it is achieved that the inlet and outlet openings are on the same side of the transformer housing. This facilitates the maintenance-related inclusion or removal of such a transformer. Preferably, a blower is provided to force cooling air through the coil segments.

In a further variant of the invention, the housing and holding structures used therein, such as, for example, the pressing bars for the transformer core are manufactured in lightweight construction, for example made of aluminum. The weight of the transformer is thereby reduced in an advantageous manner, which is particularly advantageous due to the intended mobile use of the transformer, for example in rail vehicles.

Advantageously, vibration damping and adapted to the shape of the respective bearing surfaces supporting elements are provided by which the dry transformer is supported on the support surfaces and / or fixed. By adjusting the example wedge-like and, for example, a hard rubber supporting elements on the outer shape of the respective bearing surfaces a homogeneous pressure load of the bearing surfaces is guaranteed. Due to the vibration damping properties of the support elements, both the natural oscillation of the transformer during operation, for example 16 2/3 Hz, as well as shocks due to the movement of a locomotive, for example, in which the transformer is integrated, are damped.

Following a preferred embodiment of the dry-type transformer according to the invention, interleaved winding segments are cast together. This increases the mechanical stability of the electrical part of the winding and advantageously increases the respective compressive strength. An encapsulation or a solidification of the winding takes place for example by means of an epoxy resin. Optionally, a tape-like prepreg material can also be used as layer insulation between respective winding layers, which is introduced during winding of the windings. In a final heating process, the transformer winding is heated and the B-staged resin contained in the prepreg is completely polymerized, which then leads to mechanical stabilization of the respective windings.

According to the invention, it is provided in a variant that respective first, respective second and / or respective third winding segments are galvanically connected to one another. This can be done both by means of a series connection and a parallel connection. Preferably, high voltage windings are connected in series to reduce the voltage stress and lower voltage windings for increasing the current carrying capacity in parallel. Typically, a transformer according to the invention comprises a two-limb core each having two nested winding arrangements. Of course, it is also possible to connect several respective first, second and / or third winding segments which are nested in the same winding arrangement, for example in series.

Furthermore, it is also provided according to the invention that the at least one first and the at least one second winding segment are galvanically connected in series, so that an autotransformer is formed. This optionally has several taps and is characterized by a particularly high power density.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail.

Fig. 1

einen Schnitt durch einen exemplarischen hohlzylindrischen Kühlkanal,

Fig. 2

einen ersten Schnitt durch exemplarische ineinander geschachtelte Wicklungssegmente,

Fig. 3

einen zweiten Schnitt durch exemplarische ineinander geschachtelte Wicklungssegmente,

Fig. 4

eine Schnittansicht von einem exemplarischen ersten Trockentransfor-mator sowie

Fig. 5

eine Schnittansicht von einem exemplarischen zweiten Trockentrans-formator.

Show it:

Fig. 1

a section through an exemplary hollow cylindrical cooling channel,

Fig. 2

a first section through exemplary nested winding segments,

Fig. 3

a second section through exemplary nested winding segments,

Fig. 4

a sectional view of an exemplary first dry-type as well as

Fig. 5

a sectional view of an exemplary second dry-type transformers.

Fig. 1 shows a section 10 through an exemplary hollow cylindrical cooling channel, wherein the radially inwardly and outwardly adjacent winding segments are not shown. Between a radially outer 12 and radially inner 14 boundary, a hollow cylindrical cooling channel is formed, in which in the radial direction strip-like spacer elements 24, 26, 28 are arranged, which extend along the axis of the winding. These are made for example of a glass fiber reinforced composite material or pressboard. Between the spacer elements 24, 26, 28 thereby channels 16, 18, 20, 22 are formed along the axial extent, which are inventively provided as cooling channels for flowing through air. The cooling channel is shown in its desired orientation, wherein in the lower region, the spacer elements 24, 26, 28 denser, ie with a smaller distance from each other, arranged are. Therefore, the compressive strength of the cooling channel is increased in its lower region such that the weight of a transformer or transformer core, not shown here, can be removed without deformation of the cooling channel or of the scattering channel formed by it.

Fig. 2 shows a first cut 30 by nested winding segments 32, 34, which in this case have an approximately rectangular cross-section. Such a cross-sectional shape is advantageous for increasing the fill factor or for maximum utilization of the limited space available in the underfloor area of a railway car or a locomotive. The radial spacing of the first 34 and second 32 winding segment is effected by strip-like spacer elements 40, 42, wherein between them respective cooling channels 36, 38 are formed. The nested winding segments are shown in their desired orientation, ie lying, with a support surface 44 is indicated in the lower region. To increase the compressive strength of the nested winding segments in the radial direction to the support surface 44, the distribution of the spacer elements in the lower region is compressed accordingly.

Fig. 3 shows a second section through nested winding segments 54, 56, 58, which in this case have a circular cross-section. Between the winding segments 54, 56, 58 serving as cooling channels cooling channels 60, 62 are formed, wherein the measures provided for in these spacers are not shown in this illustration. The radially inner first winding segment 54 encloses a transformer core leg 52 and, seen electrically, is a low-voltage winding, for example a 400V supply for a train heater. The radially middle third winding segment represents a high-voltage winding, for example a 15 kV winding, which is fed by a catenary of a traction power supply. The radially outer second winding 58 is a low-voltage winding and supplies, for example, the electric drive of a locomotive, not shown.

Fig. 4 shows a side sectional view 70 of an exemplary first dry-type transformer. Arranged in an aluminum housing 72 is a two-leg transformer core 86, which is enclosed on each of its legs by respective arrays of nested winding segments 82, 84. There are three nested cylindrical winding segments in each other, wherein radially between each respective hollow cylindrical cooling or stray channels are provided. At the respective lower regions of the arrangements of the nested winding segments wedge-like and the shape of the outer contour bearing surfaces of the radially outer winding segments adapted supporting elements 78 are provided from a hard rubber material, over which the weight of the windings and the transformer core are proportionally removed down. These are in turn arranged on a respective intermediate element 76, for example an aluminum strip. In the upper area, respective damping elements 88 similar in shape are provided, which enable a fixation of the windings 82, 84 or of the transformer in the housing 72, which of course do not serve for the removal of the weight. An air guide plate 74 between the winding assemblies 82, 84 serves to form a respective guide channel for coolant, which extends along the winding segments. The dimensions of the housing are, for example, 0.7m in height, 1.6m in width and 2.4m in length. Due to the horizontal arrangement, an arrangement in the underfloor area of a railway carriage is possible despite the increased space required by the cooling channels.

Fig. 5 shows a sectional view 90 of an exemplary second dry-type transformer. This corresponds essentially to that in the Fig. 4 shown, but is shown in a plan viewperpective. Arranged in a housing 112 is a two-leg transformer core 92, which is enclosed on its two legs by nested hollow-cylindrical winding segments 94, 96. The housing 112 has an inlet opening 98 and an outlet opening 100, wherein by means of air guide plates 106, 108, 110 a serpentine-like guidance of inflowing air 102 is ensured by the housing. The introduced with a blower, not shown air heats up when flowing through the inner housing in the direction indicated by corresponding arrows and then exits at the outlet opening 100 as a heated air stream 104 again.

LIST OF REFERENCE NUMBERS

10

Section through exemplary hollow cylindrical cooling channel

12

radially outer boundary of the cooling channel

14

radially inner boundary of the cooling channel

16

first cooling channel segment

18

second cooling channel segment

20

third cooling channel segment

22

fourth cooling channel segment

24

first spacer element of the cooling channel

26

second spacer element of the cooling channel

28

third spacer of the cooling channel

30

first cut through nested winding segments

32

radially outer second winding segment

34

radially inner first winding segment

36

first cooling channel segment of the nested winding segments

38

second cooling channel segment of the nested winding segments

40

first spacer element

42

second spacer element

44

bearing surface

50

second section through nested winding segments

52

Transformer core leg

54

first winding segment

56

third winding segment

58

second winding segment

60

first cooling channel

62

second cooling channel

70

Sectional view of exemplary first dry-type transformer

72

casing

74

first air baffle

76

intermediate element

78

supporting

80

air duct

82

first nested winding segments

84

second nested winding segments

86

Transformatorkernjoch

88

damping element

90

Sectional view of exemplary second dry-type transformer

92

transformer core

94

first nested winding segments

96

second nested winding segments

98

inlet port

100

outlet

102

incoming air

104

outgoing air

106

second air baffle

108

third air baffle

110

fourth air baffle

112

casing

Claims (14)

A dry type mobile transformer (70, 90) comprising a transformer core (52, 86, 92) and at least one radially inner first (34, 54) and radially outer second (32, 58) wound around a common winding axis and from the transformer core (86, 92) through-penetrated hollow cylindrical winding segment, which are nested and radially spaced from each other, so that between a hollow cylindrical cooling channel (10, 60, 62) is pronounced, provided for spacing spacer elements (24, 26, 28, 40, 42) are, which are arranged such that the cooling channel (10, 60, 62) can be flowed through in the axial direction of a coolant, characterized
in that the spacer elements (24, 26, 28, 40, 42) are shaped and arranged along the radial circumference of the cooling channel (10, 60, 62) over its axial length such that the proportionate weight of the horizontal transformer on at least one bearing surface (44 ) of the at least one second winding segment (32, 58) can be removed without a deformation of the cooling channel (10, 60, 62) takes place. Drying transformer according to claim 1, characterized in that the at least one second winding segment (32, 58) has exactly one respective preferred bearing surface (44) over which only the proportionate weight of the horizontal transformer can be ablated without deformation of the cooling channels (10, 60, 62). Drying transformer according to one of the preceding claims, characterized in that the spacer elements (24, 26, 28, 40, 42) are arranged compressed in the radial direction to the respective support surface (44), so that in the corresponding regions of the cooling channel (10, 60 , 62) results in increased radial compressive strength. Dry transformer according to one of the preceding claims, characterized in that the spacer elements (24, 26, 28, 40, 42) are strip or channel-like pronounced and preferably extend along the winding axis. Dry transformer according to one of the preceding claims, characterized in that the spacer elements (24, 26, 28, 40, 42) are formed as punctual support elements. Drying transformer according to one of the preceding claims, characterized in that a respective hollow cylindrical third (56) between the respective first (34, 54) and second (32, 58) winding segments nested winding segment is provided, wherein between the respective winding segments (32, 34, 54, 56, 58) each have a cooling channel (10, 60, 62) is provided. Drying transformer according to claim 6, characterized in that the at least one radially inner first (34, 54) and the at least one radially outer second (32, 58) undervoltage winding segment is provided and the at least one radially middle third winding segment (56) for high voltage , Dry transformer according to one of the preceding claims, characterized in that the transformer core (52, 86, 92) has exactly two legs (52) around each of which at least a first (34, 54) and a second (32, 58) winding segment are arranged. Drying transformer according to one of the preceding claims, characterized in that it is arranged in a housing enclosing it (72, 112), which has an inlet opening (98) and an outlet opening (100), wherein inside the housing (72, 112) air baffles ( 74, 106, 108, 110) arranged such that coolant entering through the inlet opening (98) along respective interleaved winding segments (30) is serpentine-like through the housing (72, 112) and cooling channels (10, 60, 62, respectively) ) or formed in them cooling channels (16, 18, 20, 22, 36, 38) is guided to the outlet opening. Drying transformer according to claim 9, characterized in that the housing (72, 112) and holding structures used therein are made in lightweight construction. Dry transformer according to one of the preceding claims, characterized in that vibration-damping and to the shape of the respective bearing surfaces (44) adapted supporting elements (78) are provided, by which the dry-type transformer is supported and / or fixed to the bearing surfaces (44). Dry transformer according to one of the preceding claims, characterized in that interleaved winding segments (30) are cast together. Drying transformer according to one of the preceding claims, characterized in that respective first (34, 54), respective second (32, 58) and / or respective third (56) winding segments are galvanically connected to each other. Dry transformer according to one of claims 1 to 12, characterized in that the at least one first (34, 54) and the at least one second (32, 58) winding segment are galvanically connected in series, so that an autotransformer is formed.

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