JP4064722B2 - Switching power transformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transformer for switching power supply in which a transformer side and a rectifying element are integrated.
[0002]
[Prior art]
In recent years, noise and energy loss due to a leakage inductance of a transformer that separates a primary side and a secondary side have become a problem with higher frequency in a switching power supply device.
[0003]
To solve this problem, there a line length between the transformer secondary winding and the rectifying device are known to the shortest, for example, to the transformer for power supply of JP-A 8-28815 No. 6 The terminal of the diode is directly connected to the end of the transformer winding, and the connection line between the transformer winding and the diode is made very short to reduce the leakage inductance.
[0004]
[Problems to be solved by the invention]
However, in such a conventional transformer for a power supply device, a strip-shaped conductive plate is used as one turn as the secondary winding, and the lead terminal of the rectifying unit is directly soldered to the winding end portion of the secondary winding. Therefore, it cannot be applied to transformer structures with multiple turns of secondary windings or transformer structures with multiple secondary windings of one or more turns. There was a problem of being.
[0005]
An object of the present invention is to provide a transformer for a switching power supply that minimizes leakage inductance by connecting and arranging rectifying elements at the shortest distance without being limited by the number of secondary windings.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0007]
The present invention provides a transformer for a switching power supply, which includes a transformer body in which a primary winding and a plurality of secondary windings are wound around a bobbin, and a plurality of rectifiers provided corresponding to the plurality of secondary windings. And a relay electrode plate that is disposed outside the secondary winding of the transformer body and connects the terminal end of the secondary winding and the lead terminal of the rectifying unit at the shortest distance to form a secondary rectifier circuit. It is characterized by that.
[0008]
Thus, in the present invention, the relay electrode plate is disposed so as to be sandwiched between the transformer secondary winding and the rectifying unit, and the wire end of the winding and the diode side lead terminal are the shortest distance from the relay metal plate. Even if a plurality of secondary windings are provided by being directly connected to each other, the rectification unit is not restricted by the connection arrangement of the rectification unit due to the interposition of the relay metal plate, and any winding structure can be used. Can be connected in the shortest distance.
[0009]
Here, the rectifier unit is accommodated two diodes connected in common cathode, the relay electrode plate is first to interconnect the A node side lead terminals of the secondary winding positive and one diode comprising an electrode plate, a second electrode plate interconnecting a node side lead terminals of the secondary winding minus side and the other diode, a third electrode plate for commonly connecting the cathode-side lead terminals of all diodes, the The three-electrode plate is a rectified plus output , and the second electrode plate is a rectified minus output.
[0010]
The switching power transformer comprises a rectifying module in which a rectifying unit is incorporated and connected to a resin package in which an electrode plate is molded with resin, and the relay electrode plate of the rectifying module is connected to the end of the secondary winding of the transformer body. And place it in the shortest position. Thus, by integrating the relay electrode plate and the rectification unit as a rectification module, assembly to the transformer body is facilitated, productivity can be improved, and cost can be reduced.
[0011]
The transformer for switching power supply according to the present invention is provided with a fitting groove for positioning the bobbin of the transformer main body in the resin package of the rectifying module, thereby facilitating the assembly and increasing the assembly accuracy.
[0012]
The relay electrode plate may be formed of a printed pattern on the base substrate. A plurality of rectifying units may be provided for one secondary winding and connected as a stack element.
[0013]
The rectifying module has a rectifying unit that is exposed to the outside with respect to the resin package, and a heat sink can be attached to the outside of the rectifying module. As a result, the diode can be efficiently cooled, and the rectifying module and the heat sink are integrated to facilitate assembly.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory diagram of a first embodiment of a transformer for switching power supply according to the present invention. FIG. 1 (A) is a front view of a transformer 1 according to the present invention, and FIG. 1 (B) is a side view thereof.
[0015]
In the transformer 1 of the present invention, a primary winding is wound around a bobbin 5 as a transformer body 2, and a core 2 a is mounted in a state where a plurality of secondary windings 7 are wound outside the bobbin 5. The primary lead terminal 8 is mounted. Diode units 3a and 3b functioning as rectifier units are connected and fixed to the side surface of the transformer body 2 via a relay electrode plate 4, thereby constituting a transformer secondary-side rectifier circuit.
[0016]
The relay electrode plate 4 includes a first electrode plate 4a, a second electrode plate 4b, and a third electrode plate 4c. The first and second electrode plates 4a and 4b are located in the center, and an inverted U-shaped third electrode plate 4c is disposed so as to straddle the first and second electrode plates 4a and 4b without contacting them.
[0017]
FIG. 2 shows a circuit configuration of the transformer 1 of FIG. 2A shows a circuit of the transformer 1, and FIG. 2B shows the relationship between the diode units 3a and 3b and the first to third electrode plates 4a to 4c constituting the relay electrode plate 4. FIG. .
[0018]
In FIG. 2A, the transformer 1 has two secondary windings 7a and 7b wound on the secondary side with respect to the primary winding 6 of the terminals P1 and P2. A rectifier circuit of diodes D1 and D2 is provided for the secondary winding 7a, and a rectifier circuit of diodes D3 and D4 is provided for the secondary winding 7b, and these rectifier circuits are arranged in parallel on the output side. Connected and taken out to output terminals O1, O2.
[0019]
In FIG. 2B, the relationship between the secondary windings 7a and 7b and the diode units 3a and 3b by the relay electrode plate 4 is clear. Diode unit 3a incorporates a diode D1, D2, the mosquito source over de commonly connected, and independent A node, Thus has anode terminals A1, A2 and the cathode terminal K1. Similarly, the diode unit 3b includes two diodes D3 and D4, and has anode terminals A3 and A4 and a cathode terminal K2.
[0020]
The secondary windings 7a, 7b and the diode units 3a, 3b are connected via the relay electrode plate 4. That is, the positive winding terminal S1 of the secondary winding 7a is connected to the first electrode plate 4a and the cathode terminal A1 of the diode unit 3a is connected. The winding terminal S2 of the secondary winding 7a is connected to the second electrode plate 4b, and the anode terminal A2 of the diode unit 3a is also connected to the second electrode plate 4b. The cathode terminal K1 of the diode unit 3a is connected to the third electrode plate 4c.
[0021]
Similarly to the secondary winding 7a side, the secondary winding 7b side is connected to the first to third electrode plates 4a to 4c, and similarly connected to the diode unit 3b side. The rectified output for the connection of the relay electrode plate 4 is such that the third electrode plate 4c connecting the cathode terminals K1 and K2 of the diode units 3a and 3b is connected to the output terminal O1, and the second electrode plate 4b. Is connected to the output terminal O2 on the negative side of the rectified output.
[0022]
FIG. 3 is an exploded view of the transformer body 2 of FIG. A bobbin 5 provided in the transformer body 2 is wound with a primary winding 6 having terminals P1 and P2. A secondary winding 7a made of a strip-shaped conductive plate is wound around a primary winding 6 wound around the bobbin 5 through an appropriate insulating material, and the winding terminals S1 and S2 are connected to the upper notch of the bobbin 5 from the notch. Take it out. After the secondary winding 7a is wound, the secondary winding 7b is wound on the outside via an appropriate insulating member, and the winding terminals S3 and S4 are taken out from the lower notch of the bobbin 5.
[0023]
In addition, the winding with respect to the bobbin 5 is not limited to this, but the secondary winding 7b may be wound around the bobbin 5, the primary winding 6 may be wound next, and the secondary winding 7a may be wound last. .
[0024]
FIG. 4 is an exploded view of the relay electrode plate side with respect to the transformer body on which the core 2a is mounted after the assembly of FIG. Since the winding terminals S1 to S4 of the secondary windings 7a and 7b wound as shown in FIG. 3 protrude on the side surface of the transformer main body 2, the first and second electrode plates 4a and 4b are attached thereto. To do. Insertion holes 9 are respectively formed at two locations of the first and second electrode plates 4a and 4b, and the winding terminals S1 to S4 are inserted therein. A third electrode plate 4c having an inverted U-shape and having an outward bent portion 10 at the center is disposed on the outside thereof.
[0025]
FIG. 5 shows an assembled state of the relay electrode plate 4 with respect to the transformer main body 2, and thereafter, the diode units 3 a and 3 b are placed at positions corresponding to the first to third electrode plates 4 a to 4 c of the relay electrode plate 4 from both sides. The connection is made according to FIG.
[0026]
In the transformer 1 of the present invention shown in the embodiment of FIG. 1 having such a structure, a plurality of secondary windings wound around the transformer body 2, in this example, two secondary windings 7a and 7b are provided. On the other hand, the relay electrode plate 4 is sandwiched between the diode units 3a and 3b, and the winding terminal and the lead terminal are directly connected at the shortest distance, so that the secondary winding of the transformer 1 can be connected. It is possible to minimize the line length from the line to the rectifying diode, thereby reducing the leakage inductance of the transformer 1.
[0027]
FIG. 6 is an explanatory view of the transformer 1 showing the second embodiment of the present invention. In this embodiment, the rectifying module 11 in which the relay electrode plate and the diode unit are integrated is assembled to the transformer body 2. It is characterized by doing so. Rectifying fitting groove 15 is formed in the module 11, here is performed positioned fitted partition plate tip 14 of both ends of the bobbin 5.
[0028]
FIG. 7 shows the rectifying module 11 of FIG. The rectifying module 11 is formed by forming a box-shaped resin package 12 opened to the outside with a resin mold. When the resin package 12 is formed with a resin mold, the first to third components constituting the relay electrode plate 4 are formed. The electrode plates 4a to 4c are embedded inside and molded integrally.
[0029]
In the embedded state in the resin package 12, the bent portion 10 of the third electrode unit 4c is exposed to the outside. Further, as shown in FIG. 4, a portion corresponding to the insertion hole 9 provided in the first electrode plate 4a and the second electrode plate 4b is an opening 12a, and the secondary winding from the transformer body 2 side is formed in this portion. At the same time that the winding terminal is inserted and connected, the diode units 3a and 3b are incorporated from the outside so that the lead terminals can be connected by soldering.
[0030]
The diode units 3a and 3b may be fixed to the resin package 12 by screwing or welding. The circuits in the embodiment of FIGS. 6 and 7 are the same as those in FIG.
[0031]
As described above, the relay electrode plate and the diode unit connected to the transformer main body 2 are integrated into the resin package 12 and configured as the rectifying module 11 so that the relay electrode plate and the diode unit are assembled to the transformer main body 2. As a result, the assembly work becomes easy, so that productivity can be increased and the cost can be reduced.
[0032]
FIG. 8 is an explanatory diagram of a transformer showing a third embodiment of the present invention. In this embodiment, the transformer body 2 is provided with four secondary windings 7a to 7d as shown in the circuit diagram of FIG. Correspondingly, rectifying modules 11a and 11b are arranged on both sides of the transformer body 2.
[0033]
FIG. 9 shows a heat sink mounting structure for the transformer 1 of FIG. The outer surfaces of the rectifying modules 11a and 11b arranged on both sides of the transformer main body 2 are heat sink mounting surfaces. That is, as shown in the rectifying module 11a, the diode units 3a and 3b incorporated outside the rectifying module 11a are exposed, and this exposed surface becomes a heat sink mounting surface, so that the heat sink 13a is fixed here by screwing or the like. Thus, the diode unit and 3a and 3b can be cooled. Similarly, the heat sink 13b is provided for the rectifying module 11b on the opposite side.
[0034]
FIG. 10 is a circuit diagram of a transformer and a rectifier circuit in the third embodiment of FIG. In the circuit diagram of this embodiment, four secondary windings 7 a to 7 d are provided on the secondary side with respect to the primary winding 6. A rectification module 11a is provided for the secondary windings 7a and 7b, and the outputs of the two rectification circuits are connected in parallel by diodes D1 to D4.
[0035]
Similarly, a rectification module 11b is provided for the secondary windings 7c and 7d, and two rectification outputs are connected in parallel by diodes D5 to D8. Therefore, two rectified output terminals O1, O2 and O3, O4 are taken out from the secondary side.
[0036]
FIG. 11 is an exploded view of the winding portion of the transformer body 2 in the transformer 1 of FIG. In FIG. 11, the primary winding 6 is first wound around the bobbin 5. Next, the secondary winding 7a is wound around the outer side of the primary winding 6 through an appropriate insulating material. As shown in the assembled transformer body 2 in FIG. S1 and S2 are taken out.
[0037]
Next, the secondary winding 7b is wound around the bobbin 5, and the winding terminals S3 and S4 are taken out to the lower side of the right side of the bobbin as shown in FIG. Subsequently, the secondary winding 7c is wound, and finally the secondary winding 7d is wound. Thus, the transformer main body 2 as shown in FIG. 12 is assembled by assembling the core 2a to the bobbin 5 around which the four secondary windings 7a to 7d are wound.
[0038]
Rectifier modules 11a and 11b are attached to the transformer body 2 from both sides. The rectification circuit shown in FIG. 10 is configured by mounting the rectification modules 11a and 11b.
[0039]
FIG. 13 shows the connection relationship between the relay electrode plate 4 embedded in the rectifying module 11a of FIG. 12 and the diode units 3a, 3b in a transparent state. The first electrode plate 4a, the second electrode plate 4b, and the third electrode plate 4c are embedded in the resin package 12 of the rectifying module 11a, and the diodes D1, D2 and the diodes D3, D3 incorporated in the diode units 3a, 3b. D4 is connected to a lead terminal as shown. As a rectified output, the third electrode plate 4c has a positive output, and the second electrode plate 4b has a negative output.
[0040]
FIG. 14 is an explanatory diagram of a fourth embodiment of a transformer according to the present invention. In the transformer 1 of the fourth embodiment, the secondary winding is wound around the transformer body 2 in the vertical direction, and the rectifying module 11 corresponding to this has a two-stage built-in structure, Furthermore, a heat sink 13 can be attached to the outside.
[0041]
FIG. 15 is a circuit diagram of the fourth embodiment of FIG. In this circuit diagram, two secondary windings 7a and 7b are provided for the primary winding 6, but two diodes are connected in parallel as rectifying diodes for the secondary windings 7a and 7b. Circuit connection as a stack diode to be used.
[0042]
That is, diode units 3a and 3b are provided for the secondary winding 7a, and the diodes D1 and D3 are connected in parallel to the line from the winding terminal S1 to form a positive stack element. At the same time, the diodes D2 and D4 are also connected in parallel to the negative line from the winding terminal S2 to form a stack element.
[0043]
Similarly, on the secondary winding 7b side, two diode units 3c and 3d are provided, and diodes D5 and D7 are connected in parallel to the + side line from the winding terminal S3 to form a stack element. Diodes D6 and D8 are connected in parallel to the − line from S4 to form a stack element. With such a stack element configuration by connecting two diodes in parallel, the current capacity of the secondary side rectified current can be increased.
[0044]
FIG. 16 is an exploded view of the transformer body 2 in the fourth embodiment of FIG. In FIG. 16, the bobbin 5 has a two-stage structure having partitions at three places, the upper and lower sides and the center. First, the primary winding 6 is wound around the bobbin 5. Subsequently winding the secondary winding 7a on the upper side of the bobbin 5, wound around a secondary winding 7b on the lower side of the bobbin 5, the respective winding terminal S1~S4 from notch above and under the central portion of the bobbin outer Take out. Finally, the core 2a divided into the top and bottom is mounted in the core mounting hole 5a of the bobbin 5.
[0045]
FIG. 17 is an explanatory diagram of the structure of the relay electrode plate in the rectifying module 11 used in the transformer 1 in the fourth embodiment of FIG. 14 and the attachment of the four diode units 3a to 3d thereto.
[0046]
In FIG. 17, the resin package portion of the rectifying module 11 is indicated by a broken line, and the first electrode plate 4a, the second electrode plate 4b and the third electrode plate 4c embedded therein are indicated by solid lines.
[0047]
FIG. 18 shows the connection of the lead terminals of the four diode units 3a to 3d to the respective electrode plates of FIG. 17, and the parallel connection of the diodes as the stack elements shown in FIG. 15 can be realized by this connection.
[0048]
FIG. 19 is an exploded view of the fifth embodiment of the transformer 1 according to the present invention. In the fifth embodiment, unlike the above-described embodiment, the secondary winding 7 is wound around the bobbin 5 using a normal enameled wire instead of a strip-shaped conductive plate. Here, the bobbin 5 is disposed horizontally, and the core 2a is mounted on both sides of the core mounting hole 5a in the horizontally mounted state, so that the transformer body is configured in a horizontally mounted structure.
[0049]
For this horizontally mounted transformer body, a rectifying module 11a is mounted on the side where the winding terminals S1, S2 are taken out from the bobbin 5, and a rectifying module 11b is provided on the side where the opposite winding terminals S3, S4 are taken out. Wear.
[0050]
Two diode units 3a and 3b are mounted on the rectifying module 11a. Two rectification modules 3c and 3d are attached to the rectification module 11b on the opposite side (not shown). The circuit configuration of the horizontal transformer 1 is the same as that shown in FIG.
[0051]
Even in the horizontal transformer 1 in this embodiment, the distance between the secondary winding of the transformer main body and the diode units 3a to 3d attached to the rectifying module 11a is the shortest distance. Leakage inductance can be reduced to a minimum.
[0052]
FIG. 20 is an exploded view of the sixth embodiment of the transformer 1 according to the present invention. In the transformer 1 of the sixth embodiment, the same bobbin 5 as shown in FIG. 19 is used, and in this case, two secondary windings 7 are wound vertically and the winding terminals S1 and S2 are placed on the lower side. At the same time, the winding terminals S3 and S4 are taken out upward.
[0053]
In this state, the core 2a is attached to the core mounting hole 5a from above and below to assemble the transformer body. The rectifying module 11 is attached to the side of such a vertically placed transformer body, and the rectifying module 11 of this embodiment is provided with diode units 3 a and 3 b for the printed pattern 17 formed on the metal base substrate 16. In addition, four winding mounting holes 18a to 18d corresponding to the winding terminals S1 to S4 on the transformer main body side are provided above and below the print pattern 17 arranged vertically in the center. A lead terminal 19 is taken out below the metal base substrate 16.
[0054]
The state after assembly by such an exploded view is as shown in the plan view of FIG. That is, the diodes 3 a and 3 B are connected to the side surface of the transformer body 2 via the metal base substrate 16. The printed pattern 17 formed on the metal base substrate 16 plays the same role as the relay metal plate provided in the already described first to fifth embodiments.
[0055]
In the embodiment of FIG. 20, the metal base substrate 16 itself functions as a heat sink, and it is not necessary to provide a separate heat sink for the diode units 3a and 3b.
[0056]
FIGS. 21, 22 and 23 (A) to (K) show various combinations of the transformer main body and the rectifying module in the transformer according to the present invention.
[0057]
21A to 21C show the case where the rectifying module 11 is assembled on one side of the transformer body 2, and the number of rectifying units corresponding to the number of secondary windings in the transformer body 2 is provided. FIGS. 21D and 21E show a case where a plurality of transformer bodies 2 are arranged for one rectifying module 11.
[0058]
FIGS. 22F and 22G show the case where the rectifying modules 11a and 11b are arranged on both sides of the transformer main body 2. FIG. 22 (H) and (I), the rectifying module 11a in which the diode units are arranged above and below the transformer main body 2 is arranged on one side or both sides.
[0059]
Further, in FIGS. 23 (J) and (K), the rectifying module 11 is arranged in a direction orthogonal to the outside of the transformer body 2. For example, in the case of FIG. Units 3a and 3b (not shown) are arranged. In FIG. 23 (K), the rectifying modules 11a and 11b are arranged in a direction orthogonal to both sides with respect to the transformer main body 2, whereby a total of four diode units 3a to 3d are arranged.
[0060]
FIG. 24 shows an example of a rectifier circuit applicable to the structure using the rectifier module in the transformer of the present invention. That is, the forward rectifier circuit 21 in FIG. 24A, the forward rectifier circuit 22 in FIG. 24B, and the double current rectifier circuit 23 in FIG. 24C can be used.
[0061]
FIG. 25 shows an example of a synchronous rectifier circuit applicable to the structure using the transformer rectifier module of the present invention. That is, the present invention can be applied to the forward synchronous rectifier circuit 24 in FIG. 25A, the forward synchronous rectifier circuit 25 in FIG. 25B, and the double current synchronous rectifier circuit 26 in FIG. 25C. In the circuit, switching elements Q1 and Q2 using FETs instead of diodes are used.
[0062]
The present invention is not limited to the above-described embodiment, includes appropriate modifications that do not impair the object and advantages thereof, and the present invention is not limited by the numerical values shown in the above-described embodiment.
[0063]
【The invention's effect】
As described above, according to the present invention, the relay electrode plate is disposed so as to be sandwiched between the transformer secondary winding and the diode unit, and the tip of the secondary winding and the diode with respect to this relay electrode plate. The lead terminal on the side is directly connected at the shortest distance, so even if multiple secondary windings are provided on the transformer, any of the relay terminals can be used without any restriction due to the connection arrangement of the diode unit. Even with such a winding structure, the diode units can be connected at the shortest distance, thereby greatly reducing the leakage inductance of the transformer, and reducing noise and improving power conversion efficiency.
[0064]
Also, by providing a rectification module that integrates the relay electrode plate and diode unit to the transformer body, and connecting it by assembling it, the assembly work on the rectifier circuit side to the transformer body is facilitated and productivity is improved. By making it, it can be made inexpensively.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a first embodiment of a transformer according to the present invention. FIG. 2 is a circuit diagram of the first embodiment of FIG. 1. FIG. 3 is an exploded view of the transformer body of FIG. FIG. 5 is an exploded view of the diode unit with respect to the relay electrode plate connected to the transformer body. FIG. 6 is a diagram illustrating a second embodiment of the transformer according to the present invention using a rectifying module. FIG. 7 is an exploded view of a diode unit for the rectifying module of FIG. 6. FIG. 8 is an explanatory view of a third embodiment of the transformer according to the present invention using two sets of rectifying modules. FIG. 10 is a circuit diagram of the third embodiment of FIG. 8. FIG. 11 is an exploded view of the transformer body of FIG. 8. FIG. 12 is an exploded view of the rectifying module with respect to the transformer body. 13 is an explanatory diagram of a connection state of a diode unit to a relay electrode plate in the rectifying module of FIG. 12. FIG. 14 is an explanatory diagram of a fourth embodiment of a transformer according to the present invention. FIG. 16 is an exploded view of the transformer body in FIG. 14. FIG. 17 is an exploded view of the diode unit in the rectifying module in FIG. 14. FIG. 18 is an explanatory diagram of the connection state of the diode unit in the rectifying module in FIG. FIG. 19 is an explanatory diagram of a fifth embodiment of a transformer according to the present invention having a horizontally placed structure. FIG. 20 is an explanatory diagram of a sixth embodiment of a transformer according to the present invention using a metal base substrate. FIG. 22 is an explanatory diagram of a combination arrangement of a main body and a rectification module. FIG. 22 is an explanatory diagram of a combination arrangement of a transformer main body and a rectification module following FIG. Circuit diagram of the synchronous rectifier circuit the circuit diagram FIG. 25 the present invention can be applied in the forward rectifying circuit diagram of a combination arrangement of the transformer body and rectifier module subsequent to 22 [24] The present invention is applicable [Description of symbols]
1: Transformer 2: Transformer body 2a: Core 3, 3a-3h: Diode unit 4: Relay electrode plate 4a: First electrode plate 4b: Second electrode plate 4c: Third electrode plate 5: Bobbin 5a: Core mounting hole 6: Primary winding 7, 7a-7d: Secondary winding 8: Primary lead terminal 9: Insertion hole 10: Bending portion 11, 11a, 11b: Rectification module 12: Resin package 12a: Opening 13, 13a, 13b: Heat sink 14: Partition plate tip 15: Fitting groove 16: Metal base substrate 17: Print patterns 18a to 18d: Winding connection hole 19: Lead terminal

Claims (6)

A transformer body in which a primary winding and a plurality of secondary windings are wound around a bobbin;
A plurality of rectification units provided corresponding to the plurality of secondary windings;
A relay electrode plate that is disposed outside the secondary winding of the transformer body and connects the terminal of the secondary winding and the lead terminal of the rectifying unit at the shortest distance to form a secondary rectifier circuit ;
With
The rectifying unit houses two diodes having a common cathode connected thereto,
The relay electrode plate includes a first electrode plate that interconnects the secondary winding plus side and the anode side lead terminal of the one diode, a secondary winding minus side, and the anode side lead terminal of the other diode. A second electrode plate to be interconnected and a third electrode plate for commonly connecting the cathode side lead terminals of the two diodes are provided, the third electrode plate being a rectified plus output, and the second electrode plate being a rectified minus output. This is a transformer for switching power supply. 2. The switching power supply transformer according to claim 1 , wherein the rectifying unit is built and connected to a resin package in which the relay electrode plate is resin-molded to form a rectifying module, and the relay electrode plate of the rectifying module and the transformer A switching power supply transformer characterized in that the terminal of the secondary winding of the main body is connected and arranged at the shortest position . 3. The switching power transformer according to claim 2 , wherein a fitting groove for positioning a bobbin of the transformer main body is provided in the resin package of the rectifying module . 2. The switching power supply transformer according to claim 1 , wherein the relay electrode plate is formed of a printed pattern of a metal base substrate . 2. The switching power supply transformer according to claim 1 , wherein a plurality of the rectification units are provided for one secondary winding and connected as a stack element . 3. The switching power supply transformer according to claim 2 , wherein the rectifying module includes a rectifying unit that is exposed to the outside with respect to the resin package, and a heat sink can be attached to the outside of the rectifying module. Switching power transformer.

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