EP0918342B1

EP0918342B1 - Slit transformer

Info

Publication number: EP0918342B1
Application number: EP98917775A
Authority: EP
Inventors: Bong Soo Jeong; Jin Ho Yang; Jin Wook 101 Ga-dong KOO
Original assignee: SAMWHA ELECTRONICS CO Ltd
Current assignee: Samwha Electronics Co Ltd
Priority date: 1997-06-13
Filing date: 1998-04-30
Publication date: 2003-08-27
Anticipated expiration: 2018-04-30
Also published as: WO1998057339A1; DE69817508D1; JP3251303B2; EP0918342A4; ATE248428T1; EP0918342A1; KR100302951B1; KR19990001403A

Abstract

The present invention is about a high frequency transfer which seeks for automatic winding method of a coil and reducing the manufacturing cost of the high frequency transfer by operating the dipping process which prevents shorting of the coil in the atmospheric pressure without vacuum device. In the high frequency transfer of the present invention, plurality of slots 150 are included at a winding part 106 of a bobbin and supporting part 129 for each of the upper core 300 and lower core 200 are fixed at the fixing part which is at an each end of the bobbin. Also, a projecting part 131 of the each upper and lower core face each other with a certain gap inside the penetrating hole 104 of the bobbin, whereas the projecting part 132a of the upper core and the projecting part 132b of the lower core are fixed to each other by contacting outside of the winding part 104 of the bobbin. The first coil and second coil being wind at the winding part 106 wind at each of the slot 150 in turns putting the gap which is formed by the projecting part 131 at the center for determining the standard distance. <IMAGE>

Description

[Brief Description Of Drawings]

Fig. 1a is a perspective view of the conventional bobbin.

Fig. 1b is a cross sectional view of the conventional bobbin.

Fig. 2a is a perspective view of the conventional bobbin where a coil is wound.

Fig 2b is a cross sectional view of the conventional bobbin where a coil is wound.

Fig. 3 is a perspective view of a core.

Fig. 4 is a perspective view of the conventional high frequency transformer.

Fig. 5a is a perspective view of bobbin of the present invention.

Fig. 5b is a cross sectional view of bobbin of the present invention.

Fig. 6 is an arrangement plan of a core which is installed at the bobbin.

Fig. 7 is cross sectional view of a high frequency transformer of a flyback method of the present invention.

Fig. 8a is a circuit plan of the high frequency transformer same as the structure in Fig. 9 and 7.

Fig. 8b is a circuit plan of the high frequency transformer which shows a structure of forming supporting output power supply by the second supporting coil being wound at the winding part of the second coil.

Fig. 8c a drawing which shows the physical structure of the second supporting coil of fig. 8b.

Fig. 9 is a circuit plan of the high frequency transformer showing a winding of a first coil and of a second coil.

Fig. 10 is a cross sectional view of the high frequency transformer of forward method of the present invention.

Fig. 11 is a perspective view of the high frequency transformer of the present invention.

Fig. 12 is a perspective view which shows the structure of other coils.

Fig. 13 is a perspective view of bobbin which shows other structures.

*Description of codes referring to important parts of the drawings.

Bobbin: 1, 101
Prop: 2a, 2b, 102a, 102b
Fixing part which fixes the supporting part of coil: 3, 7, 103, 107
Penetrating hole: 4, 104
Winding part: 6, 106
Connecting element: 8, 108
First coil: 10a, 10b, P1, P2, P-1, P-2
Second coil: 20a, 20b, S1, S2, S-1, S-2
Insulating tape: 25a, 25b, 25c, 25d
Supporting part which supports projecting part of coil: 29, 129, 229, 230
Supporting part of core: 31, 32a, 32b, 131, 132a, 231, 232a, 232b
Core: 30, 130, 200, 300, 400
Barrier tape: 35
Slot of winding part: 150
Partition of slot in winding part: 151
control circuit: 410
Switch: 415
Rectifier: 416
Capacitance: 417
First coil winding: Np
Second coil winding: Ns
Second supporting coil: S2

[Detailed Description Of The Invention] [Purpose Of The Invention] [Technical Field Of The Invention And The Conventional Technic Of The Field]

The present invention relates to a core like EER and EI (see fig to 6 and fig. 12, respectively) and a high frequency transformer including coil wound at a bobbin in the transformer which is used at all sorts of electricity and electric circuit device.
Especially, the present invention is about forming plurality of slots at a right angle to the central axis of cylindrical winding part which is formed at the bobbin of the transformer, making the method of coil winding automatic by winding the first coil and second coil at the slot and reducing the manufacturing cost of the high frequency transformer. First, explanation will be made hereinafter regarding the conventional high frequency transformer by referring to figures.

Fig. 1a is a perspective view of bobbin used in the conventional high frequency transformer and Fig. 1b is a cross sectional view of Fig. 1a. In Figs. 1a and 1b, bobbin 1 is formed with fixing part 3 which fixes supporting part of the core being located between two rectangular

hexahedron type support

2a and 2b that is formed in parallel. At the lower side of the

support

2a and 2b lead line connecting element 8 of the core is formed. At the upper part of the fixing part 3 a cylindrical winding part 6 is formed. A fixing part 7 which fixes the supporting part of the core is formed at the upper part of the winding part 6 and a penetrating hole 4 which penetrates

fixing parts

3 and 7 and winding part 6 simultaneously is formed. Bobbin 1 which has the structure of the fig. 1a could be changed into a structure shown in fig. 2a and fig. 2b (a plan view of fig. 1a) when the first coil and second coil is wound at the bobbin 1. In figs. 2a and 2b, the first coil 10a is wound around the winding part 6 before a certain length of insulating tape 25a is wound on the first coil for insulation among layers. Second coil 20a is wound on the insulating tape 25a and insulating tape 25b is wound on the second coil 20a for insulation among layers. First coil 10b is wound on the insulating tape 25b and then insulating tape 25c is wound on the first coil 10b. Second coil 20b is wound on the insulating tape 25c and insulating tape 25d is wound on the second coil 20b.

In the above mentioned structure, barrier tape 35 is wound between the first coil and the second coil which is wound near the edge of the winding part 6 of the bobbin in order to satisfy the international and domestic standard. The wound first and second coil is connected to a certain connecting element 8 which is formed at the lower side of

prop part

2a and 2b.

As shown in figs. 2a and 2b, after winding the coil at the bobbin 1, prepare two EER type cores 30 that is to say, a core in which projecting

portions

32a and 32b are projected vertically at the both end of the supporting part 29 and a projecting portion 31 is projected with the same direction of projecting

portions

32a and 32b at the center of the supporting part 29, likewise in the structure of fig. 3 and insert each of them at the both ends of the penetrating hole of bobbin 1. Then form the conventional high frequency transformer by fixing the ends of connecting

part

32a and 32b of two core 30 to contact each other as shown in fig. 4.

Because the first coil and the second coil are wound at a right angle to the center axis of the cylindrical winding part 6 in the conventional high frequency transformer as shown in fig. 2b, an insulating tape must be wound at the boundary of the first coil and second coil at the process of winding the first coil and the second coil in order to satisfy a certain standard of the transformer. In addition, in order to satisfy the certain distance between the first coil and second coil at the end of the first and second coil winding, barrier tape must be wound. In other words, after winding the first coil at the bobbin, wind insulating tape and barrier tape and then wind the second coil on the insulating tape.

Therefore, the winding process of insulating layer and the coil is divided into several manufacturing steps, winding must be done i'n person and the winding method cannot be done automatically. Also, when varnish dipping process is done to prevent the shorting of the wound coil, insulating tape is wound at and protects each of the coil layers so there is no need for vacuum device in order for the varnish to fully percolate each of the coil layers.

[Technical Subject Matter Of The Invention]

The present invention designed and invented to overcome the problems mentioned so far. This object is achieved by the apparatus according to the features of claim 1. Preferred embodiments are described in the dependent claims. The aim of the present invention is to manufacture and provide high frequency slot transformer with a reduced manufacturing cost than prior arts by removing the insulating layer and the like which exists between the wound coil. Yet another aim of the present invention is to carry out the varnish dipping process in order to prevent shorting of the coil in the atmospheric pressure without vacuum device. In order to achieve the aim of the present invention, especially to achieve the automatic coil winding method, the geometrical structure of the conventional bobbin has to be changed.

As shown in figs. 5a and 5b, bobbin 101 of the present invention comprises fixing part 103 which fixes supporting part of the core between the

prop

102a and 102b that is formed in parallel and a plurality of connecting element 108 at the lower side of the

prop

102a and 102b. Also, the invention comprises a cylindrical winding part 106 which is at the upper part of the fixing part 103 and a fixing part 107 which fixes the supporting part of the core and it is at the upper part of the winding part 106. A penetrating hole 104 which penetrates the lower part of the fixing part 103, the cylindrical winding part 106 and the upper part of the fixing part 107 simultaneously is also comprised in the present invention. In particular, the cylindrical winding part 106 should comprise plurality of slots 150 with a certain distance to be at a right angle to the central axis of the penetrating hole 104 which is formed at the cylindrical winding part 106. In the bobbin structure of the present invention the partition 151 which is formed between slot 150 should be formed with insulator and the thickness of the partition 151 of the slot should be determined after considering international standard size, characteristics and effects. All the more, the height of the partition 151 of slot is determined to maintain an appropriate distance along the coil lead line which is drawn out as connecting element of each of the transformer and winding height of the total area of the wound coil when the coil is wound at each slot.

In the high frequency slot transformer of the present invention which uses flyback method, a core 130 is included as EER type as shown in the structure of fig. 6 and projecting

parts

132a and 132b which are at a right angle to a supporting part 129 are inserted with a certain length at both ends of the supporting part 129. A projecting part 131 is fixed with the same direction of projecting

parts

132a and 132b at the central part of the supporting part 129. The length of the projecting part 131 is formed to be shorter than projecting

parts

132a and 132b so that the ends of the projecting part 131 do not contact each other and maintain a certain distance when projecting

parts

132a and 132b are fixed and two cores are arranged to face each other.

As shown in fig. 7 which depicts a cross sectional view of the high frequency slot transformer of the flyback method, the first and second coil is wound at a right angle to a central axis of the projecting part 131 at the total section where a projecting part 131 of the core is formed. Due to the t structure in which the first and second coil winding are arranged separately at each selected slot in parallel with the central axis of the projecting part 131, the leakage inductance could be higher than the conventional winding structure as a result of link operation of the magnetic field between wound coil. Therefore, coil should arranged separately according to a certain rule in order to maintain an appropriate coupling co-efficient of the first and second coil.

Also, through the appropriate division of separated first and second coil, they have to be arranged in a pattern to lower the link magnetic flux.

In the high frequency transformer slot which uses forward method instead of flyback method, there is no need to form a core as the structure shown in fig. 6. A core like EI type could be used to penetrate the penetrating hole of the bobbin of the present invention as a central core.

[Structure And Operation Of The Invention]

In the high frequency slot transformer of the present invention, the flyback method transformer is as shown in figs. 5a , 5b and 7. The flyback method transformer comprises bobbin 101, upper core 300 and lower core 200. In the bobbin 101, there are winding part 106, fixing

part

103 and 107 which are formed at both ends of the winding part 106, a penetrating hole 104 which penetrates the winding part 106, the fixing

part

103 and 107 and a plurality of connecting element 108 formed at the fixing part 103. In the upper core 300 and lower core 200 there are projecting

parts

132a and 132b are formed in the same direction at both ends of a supporting part 129 and a projecting part 131 is formed in the same direction with the

projection parts

132a and 132b at the center of the supporting part 129 In the winding part 106 of the bobbin 101, the first coil, P1, P2,..., P-1, P-2 and the second coil, S1, S2, ..., S-1, S-2 are wound.

In this high frequency slot transformer, a plurality of slots 150 is included at the winding part 106 of the bobbin 101, each supporting part 129 of the upper core 300 and lower core 200 are fixed at fixing

part

103 and 107 located at both ends of the bobbin 101, the projecting part 131 of the upper and lower core faces each other with a certain gap inside the penetrating hole 104 of the bobbin, projecting

parts

132a and 132b of the upper and lower core are fixed to each other by contacting at the outer side of winding part 106 of the bobbin, the first and second coil are wound at the winding part 106, wherein the windings of the first coil and the windings of the second coil are wound in turns at each slot 150 taking the certain gap made by the projecting part 131 as a yardstick and the lead line of the first and second coil is connected to the connecting element 108 selected at the bobbin. The coil Nf shown in fig. 7 is feedback coil.

Another high frequency slot transformer structure of the present invention is a forward method transformer as shown in figs. 5a, 5b and 10. The forward method transformer comprises a bobbin and a core. In the bobbin 101 there are winding part 106, fixing

parts

103 and 107 which are formed at both ends of the winding part 106, a penetrating hole 104 penetrating fixing

parts

103 and 107 and the winding part 106 and a plurality of connecting element 108 formed at the fixing part 103. In the core 400 there are each projecting part 232a and 232b formed in the same direction at both ends of the first supporting part 229, projecting parts 232a and 232b are formed in the same direction with a projecting part 231 at the center of the first supporting part 229 and the second supporting part 230 which contacts to the projecting

parts

231, 232a and 232b. In the winding part 106 of the bobbin 101 there are the first coil, P1, P2, ..., P-1, P-2 and the second coil, S1, S2, ..., S-1, S-2 are wound.

In this high frequency slot transformer, a plurality of slots 150 is included at the winding part 106 of the bobbin 101, the first supporting part 229 and the second supporting part 230 of the core 400 are fixed at the fixing

parts

103 and 107 located at both ends of the bobbin 101, the projecting part 231 of the core 400 penetrates the penetrating hole 104 of the bobbin and is fixed at the center of the second supporting part 230 and projecting parts 232a and 232b of the core are fixed by contacting at both ends of the second supporting part 230 from outside of the winding part 106 of the bobbin, the first and second coil wound at the winding part 106 of the bobbin wind in turns at each of the slot 150 to be symmetrical putting the center of the winding part 106 as a yardstick and a lead line of the first and second coil connects to the selected connecting element 108 of the bobbin 101. More detailed description of winding method and operation of the high frequency slot transformer of the present invention will be given hereinafter.

[Preferred Embodiment]

As shown in figs. 5a and 5b, fixing part 103 which fixes the supporting part of the core is included between the

prop

102a and 102b that are in parallel, a plurality of connecting element 108 is included in the bottom of the

prop

102a and 102b, a cylindrical winding part 106 is included at the upper part of the fixing part 103, a fixing part 107 which fixes supporting part of the core is included at the upper part of the winding part 106, a plurality of a slot 150 which has a certain distance are included at the winding part 106 and a penetrating hole 104 which penetrates lower part of the fixing part 103, cylindrical winding part 16 and the upper part of the winding part 107 simultaneously are included to form the bobbin 103.

All the other materials excluding connecting element 108 of the bobbin 101 use insulator plastic material and form as one body type.

In particular, the thickness and height of the partition 151 of the slot 150 which is included at the winding part 106 is determined after considering international standard, efficiency and the like.

Wind the first and second coil in turns at each slot 150 of the winding part 106 of the bobbin. For example, install and fix

EER type core

200 and 300 at the bobbin and form it as a structure in fig.7. The EER type core is not the only core which can be used. As in the structure shown in fig. 12, EE type core can be used and in case of using EE type core, it is appropriate to form the structure of winding part of the bobbin as shown in fig. 13. In the structure of the bobbin 101 in fig. 13, winding part 106 of the coil and penetrating hole 104 are square shape instead of cylindrical shape. Therefore, the shape of penetrating hole and the winding part can be changed according to the type of the core.

In fig. 7, each end of projecting part 131 of the upper and lower core do not contact each other at the center part of the penetrating hole 104 of the bobbin and a certain gap is formed. The first and second coil are wound in turns at each slot 150 which is formed at the winding part of the bobbin, empty one slot putting the gap formed between projecting part 131 of the core as a yardstick and wind the first coil at both slots nearby then wind the second coil at a slot nearby the slot where the first coil is wound. In other words, putting the gap formed by the core 300 and the projecting part 131 of the lower core 200 as a yardstick, the first coil P1 and P-1 is wound at both slots. The second coil S1 is wound at the outer slot of the first coil P1, second coil S-1 is wound at the outer slot of the first coil P-1, the first coil P2 is wound at the outer slot of the second coil S1, the first coil P-2 is wound at the outer slot of the second coil S-1, the second coil S2 is wound at the outer slot of the first coil P2 and the second coil S-2 is wound at the outer slot of the first coil P-2.

By forming at least four or five slots to thicken the partition of the slot as the central part and putting the above mentioned partition or one slot at the central part as a boundary and winding the first coil at both ends and the second coil at the outside, the high frequency slot transformer can be formed. However, forming the high frequency slot transformer with lots of slots 150 and by winding after several division of coils according to the winding rule, results in a more effective transformer in technic. As the number of slots are limited in case the size of the winding part is limited, it is appropriate to determine the number of slots giving consideration to the size and characteristic of the transformer.(This preferred embodiment is formed with nine slots.)

Because the first and second coil is wound in parallel with the central axis of the projecting part 131, the leakage inductance at each boundary of the first and second coil or gap part of the projecting part 131 could be higher than the conventional winding structure. Therefore, in order to maintain appropriate level of coupling coefficient of the first and second coil, arrange the gap made by the thickness of partition 151 of the slot and the width of the slot in which the second coil is not wound at the central part or the projecting part 131 of the core coil in appropriate pattern.

In particular, it is appropriate to wind the coil so that the number of winding between the P1 and P-1, the P2 and P-2, the S1 and S-1 and the S2 and S-2 is the same. It is appropriate that the winding ratio between the P1 and P2 is 1.3:1 or above so that the loss of link magnetic flux is lowered. Also, the height of the partition 151 of the slot 150 should be determined to maintain a certain space distance after considering the winding height of the total area of the wound coil and the distance with the coil which is drawn out as a connecting element when the coil is wound at each slot.

In case of attaching a switching device which has feedback coil Nf in the structure of fig. 7, for the reason that the first and second coil are wound in turns in the direction of a central axis of the cylindrical winding part, the switching device becomes unstable if the feedback coil Nf is arranged in a symmetrical pattern or a row pattern and wound due to the disagreement of the geometrical magnetic field. Therefore, it is appropriate that the feedback coil be wound at one of the P2 or P-2 of the first coil which is located at the most outer side of the winding part in order to maintain the safety of the switching device. The reason for winding the feedback coil at the winding part of the first coil is to maintain the insulating condition between the feedback coil and the second coil. For the above mentioned reason the feedback coil Nf is wound at the P-2 of the first coil in fig. 7.

Another way of winding a different type feedback coil Nf is to wind the feedback coil on the second coil because the number of slots fewer or it is difficult to obtain the distance between feedback coil and the gap of core. In case of winding feedback coil on the second coil, it is appropriate to use feedback coil coated with triple insulating layer because it is necessary to make the second coil and the feedback coil Nf to be insulated sufficiently. So, it is appropriate to wind the feedback coil at the most further winding part of the second coil from the gap of the core in the above mentioned case.

The fig. 7 structured as an equivalent circuit is as the structure shown in fig. 8. In fig. 8, a switching device comprising the feedback coil Nf, a switch 415 and regulating circuit is included and the feedback coil Nf of the switching device is connected to a high frequency slot transfer 500.

Np is the first coil winding, Ns is the second coil winding, 416 is a rectifier for rectifying output power and 417 is a smoothing capacitance. The Np of the first coil and Ns of the second coil could be wound as shown in fig. 9. In other words, it is a structure of Pi and P-1 of the first coil are wound at each slot putting the gap made by the projecting part 131 of upper core 300 and the lower core 200 as a yardstick, the second coil S-2 is wound at the outer slot of the first coil P-1, the first coil P2 is wound at the outer slot of the second coil S-2, the first coil P-2 is wound at the outer slot of the second coil S-2, the second coil S2 is wound at the outer slot of the first coil P2 and the second coil S-2 is wound at the outer slot of the first coil P-2 and the equivalent circuit. The first coil and the second coil are connected to the selected connecting element 108 of the bobbin and especially, the first coil is connected to the input connecting element and the second coil is connected to the output connecting element. The method of connecting wire between the first coil and the second coil can be connected in various ways according to the characteristics of transformer. For example, connect the P1 and P-1, P2 and P-2 of the first coil in parallel connection and the S1 and S-1, S2 and S-2 of the second coil in parallel connection. Furthermore, use lead line so that the parallel connected P1 and P-1 of the first coil is in series connection to the parallel connected P2 and P-2 of the first coil and parallel connected S1 and S-1 of the second coil is in series connection to the parallel connected S2 and S-2 of the second coil are connected to the connecting element 108.

The basic flyback structure of the high frequency slot transformer as mentioned above has the outside structure as shown in fig. 11. The most outstanding difference form the conventional high frequency slot transformer is the winding part of the bobbin is separated in several slots and the first and second coil are arranged in turns at the slot along the central axis of the winding part of the bobbin. By winding a second supporting coil on top or under the wound second coil in the basic flyback structure of the high frequency slot transformer, the second supporting coil could be used as a supporting output power. The above mentioned high frequency slot transformer where the second supporting coil is wound is equivalent to the circuit in fig. 8a.

In fig. 8b, Ns is the winding part of the second coil which functions as a main output power, Nsa, Nsb, Nsc, ...are the winding part of the second support coil which functions as a supporting output power. The physical structure of the winding of the second supporting coil is described in fig. 8c as an example.

In fig. 8c, the S1 and S2 of the second coil and the P2 of the first coil are wound at the slot of the winding part of the bobbin 101. Here, the S1+S2 of the second coil forms the main output power and the P2 of the first coil forms the main input power. S2' which winds on the S2 of the second coil is the second supporting coil. S2' of the second supporting coil functions as supporting output power as Nsa in fig. 8b. The second supporting coil S2' could be wound before winding the second coil S2 or it could be wound on the second coil S1. In other words, the second supporting coil S2' could be wound at more than one place selectively according to the function of the transformer in the area where the second coil S1 and S2 are wound and function as a supporting output power.

In the high frequency slot transformer of the present invention, even if the coil is wound in the above mentioned structure, it maintains the same characteristics with the conventional high frequency slot transformer or has better characteristics. The change in the structure of the high frequency slot transformer of the present invention allowed automatic winding of the coil which was impossible in the conventional high frequency transformer and more than 30% of manufacturing cost was reduced since there is no need to wind an insulating tape nor barrier tape separately.

The high frequency slot transformer of the forward method is different from the flyback high frequency slot transformer and has a structure as shown in fig. 10. The biggest difference between the flyback method and the forward method is that a projecting part 231 of the core which is inserted and installed in the penetrating hole 104 is not disconnected inside the penetrating hole 104 but connected in one body type.

The assembling steps or the winding steps of the forward method high frequency slot transformer is similar to the flyback method.

[Effect Of The Invention]

In the high frequency slot transformer of the present invention, a plurality of slots 150 which have a certain distance are included in the winding part 106 of the bobbin, so that usage of an insulating tape or barrier tape is not necessary for the first and second coil are wound in turns at each of the slot and the winding steps of the coil could be done automatically as shown in figs. 5a and 5b.

Also, in the conventional high frequency slot transformer it is necessary to have the varnish dipping step in the vacuum device in order to prevent shorting of the coil after winding the coil however, in the present invention the insulating tape is not wound so the varnish dipping process is possible in the atmospheric pressure without the vacuum device. Therefore, effect of the present invention lies in the facts that firstly, the winding step of the coil is done automatically, secondly, cost of the manufactured products are reduced drastically as there is no need to use an insulating tape which is used in winding and finally, stabilized products are produced and provided.

Claims

A high frequency slot transformer which comprises:

a bobbin (101) which has an elongated winding part (106) having fixing parts (103, 107) provided at both longitudinal ends of the winding part (106) and having a penetrating hole (104) extending through the winding part (106) and the fixing parts (103, 107) in longitudinal direction of the winding part (106);

the bobbin (101) further having a plurality of connecting elements (108) fixed on at least one side of the fixing elements (103, 107);

a plurality of slots (150) formed on the winding part (106) of the bobbin (101) at a right angle to the central axis of the penetrating hole (104) and being spaced from each other in longitudinal direction of the winding part (106) by partitions (151), an additional gap being arranged in the longitudinal middle of the slot arrangement, thereby dividing the slots into two sets of slots;

a core (130, 400) which comprises a first supporting part (129, 229) and a second supporting part (129, 230) which are arranged at a respective longitudinal end of the winding part, a first projecting part (132a, 232a) and a second projecting part (132b, 232b) arranged on at least one of the first and second supporting parts(129, 229, 230) and projecting in longitudinal direction of the winding part at lateral sides thereof, and a third projecting part (131, 231) arranged on the at least one of the first and second supporting parts (129, 229, 230) at a central position thereof and projecting into the penetrating hole (104) with a certain gap, the first supporting part (129, 229) and the second supporting part (129, 230) being connected and fixed to each other by at least the first and second projecting parts (132a, 232a; 132b, 232b).

first windings (P1...Pn, P-1...P-n) and second windings (S1..Sn, S-1..S-n) which are wound at the winding part (106), wherein the first windings (P1...Pn, P-1...P-n) and the second windings (S1...Sn, S-1...S-n) are wound in turns at each of the plurality of slots (150) taking said certain gap as a yardstick; and

a lead line of the first and second windings are connected to a selected connecting element (108) of the bobbin (101).
The high frequency slot transformer according to claim 1,

wherein the first projecting part (132a, 232a), the second projecting part (132b, 232b) and the third projecting part (131, 231) are arranged at the first supporting part (129, 229),

wherein the core (400) comprises an upper core (300) and a lower core (200) ;

wherein the first supporting part (129) is part of one of the upper core (300) and the lower core (200);

wherein the second supporting part (129, 230) is part of the other one of the upper core (300) and the lower core (200), wherein on the second supporting part (129, 230) a further first projecting part (132a, 232a) and a further second projecting part (132b, 232b) are arranged and project in longitudinal direction of the winding part at lateral sides thereof, and a further third projecting part (131, 231) is arranged on the second supporting part (129, 230) at a central position thereof and projects into the penetrating hole (104) of the bobbin (101); and

wherein the upper core (300) and the lower core (200) are connected and fixed to each other by the first projecting part (132a, 232a) and the further first projecting part (132a, 232a) as well as by the second projecting part (132b, 232b) and the further second projecting part (132b, 132b) at the outside of the winding part (106) of the bobbin (101) while the third projecting part (131, 231) and the further third projecting part (131, 231) faces each other with a certain middle gap inside the penetrating hole (104) of the bobbin (101).
The high frequency slot transformer according to claim 1 or 2, which is characterized in that the first and second windings (P1, P-1, P2, P-2, S1, S-1, S2, S-2) are alternately wound in the slots, starting with the first windings (P1, P-1) in the slots adjacent to the gap.
The high frequency slot transformer according to claim 3, which is characterized in that at least one or more slot is empty between the first windings (P1 and P-1).
The high frequency slot transformer according to claim 3, which is characterized in winding a feedback coil (Nf) at one outermost slot of the first windings (P2 or P-2) in respect to the gap.
The. high frequency slot transformer according to claim 3, which is characterized in winding a feedback coil (Nf) which is coated with triple insulating layer on one of the second windings.
The high frequency slot transformer according to claim 6, which is characterized in winding a feedback coil (Nf) at one outermost slot of the second windings (S2 or S-2) in respect to the gap.
The high frequency slot transformer according to claim 7, which is characterized in that a partition between the slot is insulating material and the height of the partition is higher than that of a winding side.
The high frequency slot transformer according to claim 8, which is characterized in that, with respect to the middle gap, a number of the winding of the innermost first windings (P1, P-1) is identical, a number of winding of the innermost second windings (S1, S-1) is identical, a number of winding of the outermost second windings (S2, S-2) is identical and a winding ratio between the innermost (P1, P-1) and outermost (P2, P-2) first windings is 1.3:1 or above.
The high frequency slot transformer according to claim 9, which is characterized in that the innermost first windings (P1) and (P-1) are in parallel connection, the outermost first windings (P2) and (P-2) are in parallel connection, the innermost second windings (S1) and (S-1) are in parallel connection and the outermost second windings (S2) and (S-2) are in parallel connection.
The high frequency slot transformer according to claim 10, which is characterized in that the parallel connected innermost first windings (P1) and (P-1) is in series connection to the parallel connected outermost first windings (P2) and (P-2) and the parallel connected innermost second windings (S1) and (S-1) is in series connection to the parallel connected outermost second windings (S2) and (S-2).
The high frequency slot transformer according to claim 2, which is characterized in that a second supporting winding is wound at more than one slot of the slots where the second windings (S1...Sn, S-1...S-n) are wound.