MXPA97009327A - Field of transformers of supply of power of mode conmut - Google Patents

Abstract

The present invention relates to a transformer (1) for switching mode power supply, equipped with a winding template (6) having the chambers (9), each chamber (9) containing the windings (15, 16), each winding (15, 16) has an external lateral surface (18) generated by a straight line that moves parallel to an axis (AA ') of the winding template, and characterized in that the generatrices of all the surfaces (18) The outermost of the windings (15, 16) contained in each of the chambers (9) are identically the same for all the outermost surfaces (18) of the windings (15, 16) of each of the chambers. These generatrices thus form a single cylindrical surface parallel to the axis (AA ') of the winding template (

Description

CA M PO_ DEJ RA NS TRAILERS OF THE POWER SUPPLY OF POTEN CJ A OF MODE CO NMUTADO C A MPO OF THE INVENTION The invention relates to the field of switched-mode power supply transformers. It refers to an improvement for transformers of this type.

BACKGROUND Switched-mode power supplies commonly equip most televisions and monitors that include a cathode ray tube. These power supplies operate by interrupting the current. The principle of power supplies of this type is now well known. The article "IEE transaction on Consumer Electronics 473-479" explains the benefit and working principle of power supplies of this type. These power supplies include transformers that have primary windings and secondary windings.

The invention relates to the transformer architecture. A known example of a transformer of this type for a power supply mode is described in European Patent EP 71008, tentatively in the name of Licentia Patent Wervaltung. This pate describes a transformer for a switched mode power supply, in which the "Scratches of the pyrrhome and the secondary are not produced in successive layers around a ferromagnetic core, but in adjacent chambers arranged axially at the lake's core. Each chamber is separated from the sapient by a sheet of insulating material. In figure 1, a transformer of this type is represented under general taveference 1. It has a ferrite core 2 formed by two goodbye cores 3, 4 of ferrite E, which are attached one to the 4n »by a line of adhesive 5 in order to form a right-angle tvo with a rectangular cross section to which a central part, hidden in Figure 1, is attached by means of a winding template 6; The winding plant 6 is only shown in Figure 2. It has a core 7 hollow rails, cylindrically shaped and lendicular walls 8 to this body. Only one of these walls 8 is shown in Figure 2. The windings (not ßßstran) are present in the chambers 9 formed between two walls. The cables 10, 10 'of these windings are connected to the connection pins 11, 11'. The primary windings are connected to the pins 11, and the windings secondary to the pins 11 '. All the primary connection pins 11 are located on one side of the transformer. All secondary connection pins 11 'are located on the other side of the transformer. Due to the perspective shown in Figure 1, only the primary winding wires 10 and the primary connection pins 1 1 are shown. The secondary connection cables 10 'and the secondary connection pins 1 1' are all located, for a good isolation, on a different side of the transformer. The cables 10 'of the secondaries are connected to the pins 11' of the secondaries in a technical manner similar to the connection of the cables 10 of the primary ones to the pins 1 1 of the primary. The term "other side of the transformer" means that the primary pins 11 and the pins 1 1 to secondaries lie on either side of a plane of symmetry of the core. In the case shown in Figure 1, this is the plane of common symmetry for the three branches of the Es forming each half core 3, 4 of the core 2. The term "ends 12, 12" of the primary cables 10 and secondary cables 10 * are used in the following to denote the portion of the cable 10, 10 'located between the end of a winding and a connecting pin 11 or 11'. These ends are held in place by the notches 13, 1 3 'formed on one side of the insulating walls 8. The notches 13 or 1 3 'of the wall 8 together form a comb 14 for connection of the wall 8. The combs 1 3 of the walls 8 guiding the primary cables 10 are located on the same side as the primary connection pins 11 . The combs 13 'of the walls 8 guiding the secondary cables 10' are located on the same side of the secondary connecting pins 11 '. This transformer architecture allows good isolation of the primary side, also designated as the "hot side", from the secondary side, also referred to as the "cold side". This good insulation is due to the fact that the primary and secondary windings are in the chambers 9 which are isolated from the DC one with respect to the other by the insulating walls 8 and the fact that the primary pins 1 1 and the secondary pins 11 ' they are far from each other. The dispersion inductances remain acceptable because the chambers 9 containing the primary windings and the chambers 9 'containing the secondary windings have alternating axial positions, and a fairly large number thereof exists. However, all other things being equal, this dispersion inductance increases when the switching frequency increases.

ADVANTAGES OF THE INVENTION The present invention relates to a transformer for a switched-mode power supply, of the type having cameras, as described, for example, in European Patent EP 71008 and having a small dispersion inductance, and which is one easy manufacturing while taking into account the diverse needs of the users of these transformers, all this while preserving the quality of the insulation inherent in the transformers of the chamber type. This object is achieved according to the invention by producing the winding template according to the windings it will contain. This point is specified later. It has been observed that the winding template consists of an insulating material. It includes a hollow cylinder 7. The interior of this cylinder 7 contains a part of the magnetic circuit of the transformer. The windings that constitute the primary or secondary windings are produced around this indro cylinder. The external diameter of this cylinder constitutes the internal diameter of each of the partial windings that are closest to this cylinder. The external diameter of a partial winding is the largest diameter of this winding. If a second partial winding occurs in the chamber where a first winding has already occurred, the internal diameter of this second winding is equal to the external diameter of the first winding, and its external diameter is the largest diameter of this secondary winding. . According to the invention, the outer diameters of the outermost windings contained in each of the chambers of the winding templates are the same. It should be noted that the use of the term "diameter" presupposes that the cylinder 7 is a revolving cylinder, a cylinder whose cross section consists of a circle. In the most general case, it can be a more arbitrary cylinder, that is, the volume generated by a straight line that moves parallel to itself while it is in contact with a guideline curve, this can, for example, be a cylinder with rectangular or elliptical cross section. In this general fashion case, the outer lateral surfaces of the outermost windings contained in each of the digits all coincide with the same surface of the cylinder, this cylindrical surface being parallel to the cylindrical surface of the cylinder. winding template that receives the most internal windings.

BRIEF DESCRIPTION OF THE INVENTION In summary, in its most general form, the invention relates to a transformer for supplying power in a switched mode, equipped with a winding plant having a cylindrical part of the axis AA 'and the separating walls with respect to the axis AA ', the volumes d i i mitted by two axially consecutive separating walls and the external lateral surface of the cylindrical part constituting the chambers of the winding template, each chamber contains at least one winding of conductive cable, each winding has two surfaces lateral, an internal lateral surface that is closest to the outer lateral surface of the cylindrical portion of the winding plate, and an external lateral surface that is the outer surface of this winding more distant from the external lateral surface of the template winding, one of the outer surfaces of the windings of each of the chambers constitutes the outermost surface of the windings of each of the chambers all coinciding with the same cylindrical surface parallel with respect to the external lateral surface of the winding template. Such a configuration differs from the prior art in that, in the chamber type transformers for a switch mode power supply of the prior art, the partition walls delimit the chambers whose axial lengths are all the same one respect to the other. According to the invention, these axial lengths can vary from one chamber to the other, such that different numbers of turns of the windings inside each chamber constitute windings whose outermost lateral surfaces coincide with a single cylindrical surface parallel to the cylindrical surface of the template. winding. An embodiment according to the invention contributes to reducing the dispersion inductances. Another measure also contributes to reducing these dispersions. This comprises placing the primary windings in parallel one with respect to the other, on the one hand, and the secondary windings in parallel with one another, on the other hand. Each part of the winding, for example, the part of the primary winding that contributes to a parallel primary winding, is placed in the primary chamber. This primary chamber is adjacent to a secondary chamber, which in itself contains a winding part that constitutes, with other secondary windings, a secondary parallel winding. This parallel winding architecture contributes not only to reduce the ohmic resistance of the windings, which is known, but also to reduce the productive losses by increasing the area of the coating surface of the primary and secondary windings. The term "coating surfaces" means the winding surfaces that are parallel to the partition walls. The surfaces are designated as "cladding" when they lie on either side of the separating wall itself.

B REVE D SCREWDRIVES The most general embodiment of the invention, the preferred embodiment and the variants of the latter will now be described with reference to the accompanying drawings, in which: Figure 1, already discussed, represents a perspective view of a known transformer. Fig. 2, which has already been discussed, represents a perspective view of a part of a winding template. In this part, only one of the walls of the chamber has been represented.

Figure 3 represents a half axial section of a winding stencil and the windings that it contains, equipping a prior art transformer. Figure 4 represents a schematic axial half section of a winding stencil and the windings that it contains, for a transformer according to the invention in its most general manner. Figure 5 represents a plan view of a transformer according to the invention. Figure 6 represents a half axial section on the line 6-6 in Figure 5. Figure 7 schematically represents the modes of confection for the windings of the primary and secondary windings of a preferred embodiment of a transformer according to the invention. . Figure 8 schematically represents the physical locations of the windings shown in Figure 7 in the chambers of the winding template shown in Figure 6. Figure 9 shows a plan view of one of the partitioning walls according to the prior art.

I I Figure 10 represents a plan view of at least one of the separating walls of a winding template of a transformer according to the invention. In all the figures, the elements that fulfill the same functions have the same reference numbers. Figure 3 represents a half axial section of a winding plant 6 carrying the primary windings 1 5 housed in the chambers 9 of the winding template 6, and the secondary windings 16 housed in the chambers 9 'of the plant the one of winding 6. Cameras 9 and 9 'are arranged alternately to provide good coupling. The volume of each chamber is delimited by a surface 1 7 belonging to the hollow tube 7 of the axis AA 'of the winding template 6 and by the walls 8 perpendicular to the axis AA'. In the example shown, there are three chambers 9 containing the primary windings and three chambers 9 'containing the secondary windings. All chambers have the same volume because the axial separations of two consecutive walls are equal to each other. The reference numbers 9-1, 9-2, 9-3 have been assigned to the primary cameras. Secondary chambers have been assigned the reference numbers 9'-4, 9'-5, 9'-6.

The chamber 9-1 contains a part 1 5a of a primary working winding, the chamber 9-2 contains another part 15b of the same winding and the chamber 9-3 contains at least one last part 15c of the same winding. The windings 15a, 15b, 1 5c are mounted in series, and are connected to the pins 1 1, for example, by welding. Other primary windings, one 15e for control, and the other 15d for feedback, are housed in chamber 9-2. Chamber 9-2 thus contains three windings or part of winding produced one on top of the other. A second winding is referred to as being above a first winding when the internal diameter of the second winding is equal to the external diameter of the first winding. The secondary chamber respectively contains the windings 16a in the chamber 9'-4, 16b in the chamber 9'-5 and 16c in the chamber 9'-6. These first three windings of the secondaries are connected in parallel, and they are also connected on the pins 1 1 'of the secondaries, for example, by welding. The winding parts 16d, 16e and 16f connected in series are housed above the windings 16a, 16b, 16c respectively. Finally, a winding 16g is housed above the winding 16f in the hoist 9'-6. In general, the primary and secondary windings consist of winding parts housed in several chambers and connected in series or in parallel as required. The architectures of this type have the purpose of optimizing the coupling of the primary-secondary, reducing the ohmic losses, obtaining several voltages required in the secondary, and the assembly is sized according to the cooling means in order to obtain a temperature of acceptable operation. The return numbers of the windings in the primary and secondary windings are chosen in order to obtain the desired voltages in the secondary while minimizing the ohmic losses (copper losses) and the losses or magnetic leakage (core losses). Based on the calculations and tests carried out, the transformers are constructed, which, for example, have the technical characteristics of the transformer shown in Figure 3, in which the windings are produced as indicated above. In the example shown, it can be seen that the various external diameters of the windings or parts of the windings that are more distant outwards are unequal, in such a way that the lateral surface of these windings has a crenellated appearance. This is due to the fact that the cameras 9 have equal volumes. Similarly, the diameters of the cables have been chosen mainly due to their ohmic characteristics, comprising the considerations regarding the volumes occupied by the windings only in such a way that the obtained transformers are not too bulky and too heavy. According to the invention, in order to minimize the magnetic losses and consequently the ohmic losses, the cameras that are produced, the diameters of the cables are chosen and the numbers of the windings are selected not only based on the considerations already mentioned in the description of the prior art as shown in Figure 3, but also by adding an additional parameter consisting of the outer diameter of the outermost winding of each chamber. According to the invention, the outermost diameters of each chamber are equal to each other. A hypothetical embodiment of the invention is that shown in Figure 4. This figure represents a half section on an axial plane of a winding template 6 provided with primary windings or parts of windings 15 and secondary windings 16. In this hypothetical example, the shapes and volumes of the chambers 9 consist of secant partitions 8 with respect to the boundary surface 1 7 of a central cylinder 8, they have shapes and volumes that are not necessarily similar or equal. The walls 8-1, 8-2 not perpendicular to the axis AA 'define a chamber 9-1, each cross section of which on an axial plane have a trapezoid shape, have been intentionally represented in this hypothetical example. The secant walls 8-3, 8-4 with respect to the limit 1 7, each cross section of which on an axial plane is curved, have also been represented. With the limit 1 7, these walls define a chamber 9-3, of which each cross section on an axial plane has the shape shown in Figure 4. In each chamber 9, the section of the surface 18 of the windings that are contained in it is a straight line CC segment. Each segment CC of straight line of each of the chambers 9 belongs to the same line BB 'straight parallel to the axis AA' of the central part 7 of the winding template 6. The same applies with respect to each of the sections of the winding template on an axial plane. In order to obtain this result, the person skilled in the art can vary parameters such as: - the shape of each chamber, - the diameter of the cables constituting the various windings, - the addition of windings connected in parallel to the first windings.

These considerations will arise after defining, in a known manner, the number of turns of the windings and their distribution in the various cameras. In the most common cases, the cost of producing the equipment to manufacture the winding templates will also be given importance. A preferred embodiment of a transformer according to the invention will now be described with reference to Figures 5 to 9. Figure 5 depicts a plan view of a transformer according to the invention. This transformer has the general form of that shown in Figure 1. The upper part of the transformer is the opposite side to the connecting pins 1 1, 1 1 '. Figure 5 shows the upper part of the nucleus 2, the parts of the winding template 6 and, in particular, a lower part 19 of this winding template that carries the pins 1 1, and the comb parts 14, 14 'of the primary side and the secondary side. Figures 6 and 8 are enlarged half-sections on 6-6 of the transformer shown in Figure 5. For the sake of clarity, the windings are not shown in Figure 6.

Figure 6 shows the winding template 6 and this part of the core 2 which is housed in the central part 7 of the winding template 6. The walls 8 perpendicular to the axis AA 'of the central part 7 delimit, with the surface 17 of this central part, the cameras 9 directed to accommodate the windings. The central part 7 is a cylinder of revolution. The outermost surface of each of the windings housed within each chamber, and all of the windings contained in the various chambers, is a cylindrical surface of revolution in this embodiment. The outer diameters of the outermost windings of each of the chambers are all equal to each other. It can be seen that the heights of the chambers, that is to say, the distance of separation, measured in parallel with respect to the axis AA ', between two consecutive walls are not necessarily equal with respect to one another. In the case where the wires constituting the windings have the same diameter, then the height of the chambers is inversely proportional to the number of turns of the windings contained in each chamber. In the case where the number of turns of the windings is the same, but when the diameter of the cables is different, then the height of the chambers is proportional to the square of the diameter of the cables that IK they are contained in it. Naturally, the calculations given above are possible only if the height of the chambers is large compared to the diameter of the cables that are housed therein. The transformer chambers 9 in Figure 6 have been numbered C1 to C9. For each camera, the following table gives the number of turns of the windings that are contained in it, and the diameters of the cables that are used. CAMERAS NUMBERS OF TURNS CABLES MM CS 83 0.2 Cf 47 0.2 C7 16 0.315 Cf 44 0.2 Cf 95 0.2 C4 16 0.315 C3 89 0.2 C2 47 0.2 Cf 83 0.2 In the example that is represented, each camera only has the cables that have the same tetro, in order to simplify the manufacture. If a tare contains a plurality of windings, it is i and naturally, it is possible that these windings use cables of different diameter. For each primary and secondary winding, the Figures 7 and 8 represent their connection mode (in parallel or in series) and their location within each of the cameras 9. The primary side of the transformer represented on the left side of Figure 7 has three winding groups. A first group of windings 20 includes four windings connected in parallel between the pins 10 on the primary side. There are 9 pins indexed B1 to B9.

The 4 windings of group 20 are indexed as N1, N5, N8 and N17. A second group of windings 21, which includes two windings connected in series and located with one another on terminal 10 indexed as B4, are connected between terminals 10 indexed as B3 and B5.

The windings of this second group are indexed as N12 and N13. Finally, the third group of primary windings 22, which is composed of two windings indexed as N10 and N11 connected in series in terminal 10 indexed as B7, are connected between terminals 10 B6, B8.

The secondary line represented on the right side of Figure 7 also has three groups of windings. A first group 23 includes only one winding designated N6, connected between the secondary terminals 1 1 * designated B1 6 and B 1 7. A second group 24 includes only one winding as N 7, connected between the secondary terminals 1 1 ' designated as B1 1 and B12. Finally, a third group 25 includes three subgroups of windings connected in series. A first subgroup 26 includes three windings connected in parallel between terminals 1 1 'indexed as B12, B1 3. These three windings are indexed as N2, N9 and N14. A second subgroup 27 includes two parallel windings that are indexed as N3, N1 and are connected between the indexed terminals as B 1 3, B14. Finally, the third subgroup 28 includes two parallel windings that are indexed as N4, N16 and are connected between the indexed thermics as B14, B15. The various windings are housed, as shown in Figure 8, by increasing the index number of the winding from a camera indexed as C1 to a camera indexed as C9. The primary windings are housed in chambers 9 indexed as C1, C3, C5, C7 and C9. Each of the windings N1, N5, N8, N1 7 which are connected in parallel and form the group 20 are housed by themselves in the chambers C 1, C3, C5 and C9 respectively. The winding groups of the secondary are housed in the cameras 9 'indexed as C2, C4, C6 and C8. It can thus be observed that the cameras with even index of the secondary one alternate with the cameras with non index that contain the primary windings. With the exception of the extreme C1 and C9 chambers, a chamber containing primary windings is adjacent to two chambers containing secondary windings. In the example shown, where the extreme chambers C1 and C9 are chambers containing primary windings, each of the chambers containing secondary windings is adjacent to two chambers containing primary windings. The group of secondary windings 23 including the winding N6 is housed in the chamber C4. The group of windings 24 including the winding N 7 are housed with the winding N6 of group 23 in the same chamber C4. The chamber C4 includes only the windings N6 and N 7. The windings of the group of the secondary windings 25 have their windings housed in the secondary chambers indexed as C2, C6 and C8. The windings N2, N3 and N4 in series of the subgroups 26, 27 and 28 are housed in the chamber 9 'indexed as C2, which does not contain other windings. Finally, the winding N9 of subgroup 26 is housed only in chamber C4. The number of turns of the parallel windings N2, N9 and N14 are respectively 41, 44 and 41. These numbers are adjusted in such a way that currents of the same value are obtained in each of these three windings in paral elo. These adjustments are made when the prototypes are produced to equalize the ohmic losses and therefore the temperatures in each of these three windings. The same is done for the two parallel windings N3, N4 on the one hand, and N1 5, N16 on the other. The result achieved by this is to distribute the ohmic losses in each of the chambers C2, C6 and C8 and therefore reduce to a minimum the maximum temperature obtained in the chamber. Similarly, in the primary, the number of turns of each of the parallel windings N1, N5, N8, N1 7 are adjusted in order to obtain equal currents in each of the windings and therefore equal the Ohmic losses in each of the cameras C1, C3, C5 and C9. The maximum temperature obtained in a chamber is thus reduced to a minimum. The fact that each of the primary windings N1, N5, N8, N1 7 connected in parallel is in an adjacent chamber on one side at least to a chamber that itself contains a secondary winding, forming part of a set of secondary windings connected in parallel, contributes to increase the areas of the coating surfaces of the primary and secondary windings. This increase in the area of the coating surfaces increases the coupling between the primary and secondary surfaces and therefore contributes to minimize the dispersion inductance. When it is fitted to the control chassis of a cathode ray tube, a transformer according to the invention thus contributes to reducing the parasitic signals whose risk is to distort the image formed on this tube. In an advantageous embodiment, at least the partition walls between two chambers containing windings or winding parts are equipped with two combs for holding the ends of the windings. The difference between a separating wall according to this embodiment of the invention and a wall of the prior art is represented by Figures 9 and 10.

Figure 9 represents a plan view of a separating wall 8 according to the prior art. This substantially rectangular wall is equipped with a comb 14 on one of its sides. This comb is used to hold the ends 12 of the windings, from the end of the winding to a connection pin 11. This comb is located on the primary side or on the secondary side depending on whether the windings located in chamber 9, which itself is located above this wall, are primary or secondary windings. According to the embodiment of the invention, at least one of the walls 8 is provided with two combs, one 14 on the side of the primary and the other 14a on the side of the secondary. Each of the combs is in a substantially symmetrical position with the position of the other with respect to a middle axis of the wall. The term "middle axis" means an axis that is parallel or perpendicular to the plane of the wall and passes through a point of symmetry of the wall or equidistant from two opposite edges of the wall. In the example shown in Figure 10, the axis BB 'passing through the point 0 which is the center of the tube 7, contained in the plane of symmetry of the core 2 and in the plane of the wall, is a middle axis. An axis that passes through 0 and is perpendicular to the plane of the wall is also a middle axis.

The chamber 9 located immediately above this wall can equally well be a chamber containing primary windings or secondary windings. It is known that a power supply can be controlled on the primary side or the secondary side. Therefore, according to this embodiment, the location of the chamber containing the control windings is predetermined when the winding template is molded, but the choice of the control side can be determined when the windings are produced. according to the client's requirements. This provides greater flexibility in production.

Claims (12)

REIVINDI CATIONS

1 . A chamber transformer for switched mode power supply, equipped with a winding jig having a cylindrical part of the axis AA 'and the separating walls with respect to the axis AAa, the volumes delimited by two axially consecutive separating walls and the lateral surface The external part of the cylindrical part constitutes the chambers of the winding template, each chamber contains at least one primary or secondary winding of the conductor cable, each winding has two lateral surfaces, an internal lateral surface that is closer to the external lateral surface of the For the cylindrical part of the winding template, one of the internal surfaces of the windings of each of the chambers constituting the innermost surface of the windings of this chamber, such innermost surface coincides with the external lateral surface of the winding template , and an external lateral surface that is the external surface of this dev The outer surface of the winding template is one of the outer surfaces of the windings of each of the chambers and constitutes the outermost surface of the windings of this chamber, whose transformer is characterized in that the outermost surfaces of the winding the windings of each of the chambers coincide with the same cylindrical surface parallel to the external lateral surface of the winding template.

2. The transformer according to claim 1, characterized in that at least one of the primary windings consists of at least three partial windings connected in parallel, each of the partial windings is insulated in a chamber, the chambers containing these windings, they are each adjacent to a chamber containing secondary windings.

3. The transformer according to claim 1, characterized in that a primary winding consists of four partial windings connected in parallel, each partial winding is insulated in a chamber.

4. The transformer according to claim 1, characterized in that a secondary winding consists of at least two partial windings in parallel, each of the partial secondary windings is housed in a 2S chamber adjacent on one side to at least one chamber containing a primary winding.

5. The transformer according to claim 4, characterized in that one of the secondary windings comprises three partial windings connected in parallel.

6. The transformer according to claim 2, characterized in that the number of turns of each of the partial primary windings connected in parallel, is such that the same value results from the same for the current flowing in each of these partial windings. .

7. The transformer according to claim 4, characterized in that the number of turns of each of the partial secondary windings connected in parallel is such that the same value results from them for the current flowing in each of these partial windings.

8. The transformer according to claim 2, characterized in that a secondary winding consists of at least two windings 2 and partials in parallel, each of the partial secondary windings is housed in an adjacent chamber on one side at least to a chamber containing a winding of the primaries.

9. The transformer according to claim 8, characterized in that the number of turns of each of the primary primary windings connected in parallel is such that the same value results from the same for the current flowing in each of these partial windings.

10. The transformer according to claim 8, characterized in that the number of turns of each of the secondary windings connected in parallel is such that the same value thereof results for the current flowing in each of these partial windings.

11. The transformer according to claim 9, characterized in that a primary winding includes four partial windings connected in parallel, and because one of the secondary windings comprises three partial windings connected in parallel, the partial windings of the secondary which are connected in parallel are each housed in chambers adjacent to two chambers containing primary windings.

12. The transformer according to one of claims 1 to 11, characterized in that at least one of the separating walls includes two combs, one of the combs guides the primary cables, and the other guiding the secondary cables.