JP2018022765A - Transformer - Google Patents

Abstract

A transformer capable of reducing winding loss is provided. A first primary winding (31) is arranged between a first secondary winding (41) and a fourth secondary winding (44), and a second secondary winding (42) and a third The second primary winding 32 is arranged between the secondary winding 43 and the secondary winding 43. The first secondary winding 41 and the first primary winding 31 are adjacent to each other and overlap, the first primary winding 31 and the fourth secondary winding 44 are adjacent to each other and overlap, The second secondary winding 43 and the third secondary winding 43 are adjacent to each other and overlap, the third secondary winding 43 and the second primary winding 32 are adjacent to each other and overlap, and the second The primary winding 32 and the second secondary winding 42 are adjacent to each other and overlap. [Selection diagram] FIG.

Description

  The present invention relates to a transformer having an intermediate tap.

  In a circuit such as a full-bridge system or a half-bridge system, an intermediate tap transformer is used. In the transformer having the intermediate tap structure, the secondary winding is constituted by two windings, and the secondary windings are alternately conducted.

  In Patent Document 1, a thin large current transformer is disclosed by using FIGS. Specifically, as shown in FIG. 8, the primary winding 200 includes a first primary winding 201 and a second primary winding 202, and the first primary winding 201 and the second primary winding 202 are Connected in series. The secondary winding 210 includes a first secondary winding 211, a second secondary winding 212, a third secondary winding 213, and a fourth secondary winding 214. The wire 211 and the second secondary winding 212 are connected in series, the third secondary winding 213 is connected in parallel to the first secondary winding 211, and the fourth secondary winding 214 is the second secondary winding 214. The secondary winding 212 is connected in parallel. Each winding (first primary winding 201, second primary winding 202, first secondary winding 211, second secondary winding 212, third secondary winding 213, fourth two The next winding 214) has a planar structure and is laminated. The first primary winding 201 is below the first secondary winding 211, the third secondary winding 213 is below the first primary winding 201, and the third secondary winding 213 is below A fourth secondary winding 214, a second primary winding 202 below the fourth secondary winding 214, and a second secondary winding 212 below the second primary winding 202. Has been placed.

Japanese Patent No. 4059396

  However, when a current flows in the direction indicated by the solid line in the first primary winding 201 and the second primary winding 202 in FIG. 8, an eddy current is formed in the fourth secondary winding 214 and the first When current flows in the direction indicated by the broken line in the primary winding 201 and the second primary winding 202, an eddy current is formed in the third secondary winding 213, and the winding loss increases.

  An object of the present invention is to provide a transformer that can reduce winding loss.

  In the first aspect of the present invention, a core, a first primary winding wound around the core, and a second primary wound around the core and connected in series to the first primary winding. A winding, a first secondary winding wound around the core, a second secondary winding wound around the core and connected in series to the first secondary winding, and An intermediate tap provided between the first secondary winding and the second secondary winding, and a third tap wound around the core and connected in parallel to the first secondary winding A transformer having a secondary winding and a fourth secondary winding wound around the core and connected in parallel to the second secondary winding, wherein the first secondary winding The first primary winding is disposed between a wire and the fourth secondary winding, and the first secondary winding is disposed between the second secondary winding and the third secondary winding. Two primary windings are arranged, the first two A winding and the first primary winding overlap adjacent to each other, the first primary winding and the fourth secondary winding overlap adjacent to each other, and the fourth secondary winding And the third secondary winding overlap with each other, the third secondary winding and the second primary winding overlap with each other, and the second primary winding and the The gist is that the second secondary winding overlaps with each other.

  According to the first aspect of the present invention, the first secondary winding and the first primary winding are adjacent to each other and the first primary winding and the fourth secondary winding are mutually connected. Adjacent to each other, the fourth secondary winding and the third secondary winding overlap adjacent to each other, the third secondary winding and the second primary winding overlap adjacent to each other, The second primary winding and the second secondary winding are adjacent to each other and overlap. When the first primary winding and the second primary winding are energized, the first secondary winding and the third secondary winding, or the second secondary winding and the fourth secondary winding Current flows through the secondary winding. Therefore, since there is no winding that prevents the magnetic field generated by energization of the first primary winding and the second primary winding, winding loss is reduced.

  According to a second aspect of the present invention, in the transformer according to the first aspect, when a current flows in a first direction with respect to the first primary winding and the second primary winding, the first Current is passed through the secondary winding and the third secondary winding, and the current flows in the second direction with respect to the first primary winding and the second primary winding. A bridge circuit for passing current through the secondary winding and the fourth secondary winding on the primary side, and a first diode is connected to one end of the first secondary winding and the second The gist is that a second diode is connected to one end of the secondary winding.

According to the second aspect of the present invention, current can flow in the first direction and the second direction with respect to the first primary winding and the second primary winding.
The transformer according to claim 1 or 2, further comprising a heat dissipating member, wherein the first secondary winding and the first primary winding are arranged between the first secondary winding and the first primary winding. Between the primary winding of the first and the fourth secondary winding, between the fourth secondary winding and the third secondary winding, between the third secondary winding and the second secondary winding. Between the two primary windings and between the second primary winding and the second secondary winding may be molded with resin.

  According to the present invention, winding loss can be reduced.

The schematic exploded perspective view of the transformer in an embodiment. The schematic sectional drawing of a transformer. The electrical block diagram of a power converter device. Sectional drawing which shows the detail of a transformer. The schematic exploded perspective view of another example of a transformer. The schematic sectional drawing of the transformer of another example. The electrical block diagram of the power converter device of another example. The schematic exploded perspective view for demonstrating background art.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the transformer 10 includes a core 20, a primary winding 30, and a secondary winding 40.

  The core 20 is an EI type core, and is configured by combining an E type core 21 and an I type core 22. The E-shaped core 21 has a rectangular plate-like body portion 21a extending in the horizontal direction, a central magnetic leg 21b protruding from the center of one surface of the body portion 21a, and one surface of the body portion 21a. And both side magnetic legs 21c and 21d projecting from the end portion. The center magnetic leg 21b has a columnar shape, and the both side magnetic legs 21c and 21d have a columnar shape. The I-type core 22 has a rectangular plate shape and extends in the horizontal direction. Then, the tip surface of the center magnetic leg 21b of the E-type core 21 and the I-type core 22 are abutted, and the tip surfaces of both side magnetic legs 21c and 21d of the E-type core 21 and the I-type core 22 are abutted. . A primary winding 30 and a secondary winding 40 are wound around the central magnetic leg 21 b of the E-type core 21. Thereby, a closed magnetic circuit is formed.

  The primary winding 30 includes a first primary winding 31 and a second primary winding 32. The second primary winding 32 is connected in series with the first primary winding 31. The first primary winding 31 and the second primary winding 32 are configured by alpha winding. For example, the number of turns of the first primary winding 31 is “7”, and the number of turns of the second primary winding 32 is “7”.

  The secondary winding 40 includes a first secondary winding 41, a second secondary winding 42, a third secondary winding 43, and a fourth secondary winding 44. For example, the number of turns of the first secondary winding 41 is “1”, the number of turns of the second secondary winding 42 is “1”, and the number of turns of the third secondary winding 43 is “1”. The number of turns of the fourth secondary winding 44 is “1”.

  The first primary winding 31 and the second primary winding 32 are arranged in a plane. The first secondary winding 41, the second secondary winding 42, the third secondary winding 43, and the fourth secondary winding 44 are arranged in a plane. 1st primary winding 31, 2nd primary winding 32, 1st secondary winding 41, 2nd secondary winding 42, 3rd secondary winding 43, 4th secondary winding 44 are laminated. The second primary winding 32 is connected in series to the first primary winding 31.

An intermediate tap (terminal) 50 is provided between the first secondary winding 41 and the second secondary winding 42.
The third secondary winding 43 is connected in parallel to the first secondary winding 41. The fourth secondary winding 44 is connected in parallel to the second secondary winding 42.

  As the laminated structure of the windings 31, 32, 41, 42, 43, 44, the uppermost stage is the first secondary winding 41, and the first primary winding 31, the fourth A secondary winding 44, a third secondary winding 43, a second primary winding 32, and a second secondary winding 42 are arranged.

  That is, the first primary winding 31 is arranged between the first secondary winding 41 and the fourth secondary winding 44. A second primary winding 32 is disposed between the second secondary winding 42 and the third secondary winding 43. The first secondary winding 41 and the first primary winding 31 are adjacent to each other and overlap each other. The first primary winding 31 and the fourth secondary winding 44 are adjacent to each other and overlap each other. The fourth secondary winding 44 and the third secondary winding 43 are adjacent to each other and overlap each other. The third secondary winding 43 and the second primary winding 32 overlap each other adjacent to each other. The second primary winding 32 and the second secondary winding 42 are adjacent to each other and overlap each other.

As shown in FIG. 3, the power converter in this embodiment has a half-bridge configuration.
The power conversion apparatus steps down the voltage of the DC power supply 65 to 1/14, for example, and outputs it to the load 75. The power conversion device includes an H-type bridge circuit 60, diodes 71 and 72, a coil 73, and a capacitor 74. A bridge circuit 60 is connected to the primary winding 30 of the transformer 10. In addition, diodes 71 and 72 are connected to the secondary winding 40 of the transformer 10.

  The primary side bridge circuit 60 includes switching elements 61 and 62 and capacitors 63 and 64. The switching elements 61 and 62 are constituted by MOSFETs. Switching element 61 and switching element 62 are connected in series between the positive and negative terminals of DC power supply 65. Capacitors 63 and 64 are connected in series between the positive and negative terminals of the DC power supply 65.

  Between the intermediate point of the switching elements 61 and 62 and the intermediate point between the capacitors 63 and 64, a primary winding 30, that is, a series circuit of the first primary winding 31 and the second primary winding 32 is connected. ing. Then, the switching element 61 and the switching element 62 are alternately turned on and off alternately, and ½ of the voltage of the DC power supply 65 is alternately applied to the primary winding 30 in a state of different polarity.

  The anode of the diode 71 is connected to one end of the first secondary winding 41 in the secondary winding 40. The anode of the diode 72 is connected to one end of the second secondary winding 42 in the secondary winding 40. The cathode of the diode 71 and the cathode of the diode 72 are connected, and one end of a coil 73 is connected to both the cathodes. A capacitor 74 is connected between the other end of the coil 73 and the intermediate tap 50. A load 75 is connected between the other end of the coil 73 and the intermediate tap 50.

  As shown in FIGS. 1 and 3, by providing the bridge circuit 60 on the primary side, a current flows in the first direction as shown by the solid lines with respect to the first primary winding 31 and the second primary winding 32. In this case, a current flows through the first secondary winding 41 and the third secondary winding 43. Further, when a current flows in the second direction as indicated by a broken line with respect to the first primary winding 31 and the second primary winding 32, the second secondary winding 42 and the fourth secondary winding are provided. Current flows through line 44.

  A diode 71 as a first diode is connected to one end of the first secondary winding 41, and a diode 72 as a second diode is connected to one end of the second secondary winding 42. Specifically, the anode side of the diode 71 as the first diode is connected to one end of the first secondary winding 41, and the second diode 42 is connected to one end of the second secondary winding 42. The anode side of the diode 72 is connected.

The details of the transformer 10 will be described with reference to FIG.
The heat dissipation member 100 is provided, and the I-type core 22 is disposed on the heat dissipation member 100.
A first secondary winding 41 is disposed on the substrate 111. A first primary winding 31 is disposed on the substrate 112. A fourth secondary winding 44 is disposed on the substrate 113. A third secondary winding 43 is disposed on the substrate 114. A second primary winding 32 is disposed on the substrate 115. A second secondary winding 42 is disposed on the substrate 116. Each winding 31, 32, 41, 42, 43, 44 is resin-molded. That is, the resin 90 is disposed between the substrate 111 and the first primary winding 31 and the resin 90 is disposed between the substrate 112 and the fourth secondary winding 44. Further, the resin 90 is disposed between the substrate 113 and the third secondary winding 43 and the resin 90 is disposed between the substrate 114 and the second primary winding 32. Further, a resin 90 is disposed between the substrate 115 and the second secondary winding 42.

  In this way, between the first secondary winding 41 and the first primary winding 31, between the first primary winding 31 and the fourth secondary winding 44, the fourth secondary winding. Between the winding 44 and the third secondary winding 43, between the third secondary winding 43 and the second primary winding 32, and between the second primary winding 32 and the second secondary winding. The space between the wires 42 is molded with a resin 90.

Further, the first secondary winding 41 and the third secondary winding 43 are electrically connected. The second secondary winding 42 and the fourth secondary winding 44 are electrically connected.
Next, the operation will be described.

Switching elements 61 and switching elements 62 in FIG. 3 are turned on alternately.
At this time, when one switching element 61 is turned on, a voltage (+ V / 2) half that of the DC power supply 65 is applied to the primary winding 30 (two primary windings 31 and 32 connected in series). In the windings 31 and 32, current flows in the first direction as indicated by solid lines in FIGS. Then, a current flows through the first secondary winding 41 and the third secondary winding 43 in the secondary winding 40 as indicated by a solid line, and a current flows through one diode 71. At this time, as shown in FIG. 1, a magnetic flux φ1 is generated around the first primary winding 31, and a magnetic flux φ2 is generated around the first secondary winding 41. Is the opposite direction, and the magnetic flux is canceled out. Similarly, a magnetic flux φ3 is generated around the second primary winding 32, and a magnetic flux φ4 is generated around the third secondary winding 43. The direction of the magnetic flux φ3 and the direction of the magnetic flux φ4 are opposite, Is offset.

  In addition, when the other switching element 62 is turned on, a voltage (−V / 2) half that of the DC power supply 65 is applied to the primary winding 30 (two primary windings 31 and 32 connected in series). In the windings 31 and 32, current flows in a second direction opposite to the first direction as indicated by broken lines in FIGS. Then, current flows through the second secondary winding 42 and the fourth secondary winding 44 in the secondary winding 40 as indicated by a broken line, and current flows through the other diode 72. At this time, as shown in FIG. 1, a magnetic flux φ5 is generated around the first primary winding 31, and a magnetic flux φ6 is generated around the fourth secondary winding 44. The direction of the magnetic flux φ5 and the direction of the magnetic flux φ6 Is the opposite direction, and the magnetic flux is canceled out. Similarly, a magnetic flux φ7 is generated around the second primary winding 32 and a magnetic flux φ8 is generated around the second secondary winding 42. The direction of the magnetic flux φ7 and the direction of the magnetic flux φ8 are opposite to each other. Is offset.

  In the case of the configuration of FIG. 8, the loss increases due to the non-uniform distribution of current density. That is, an eddy current is formed in the fourth secondary winding 214 and the third secondary winding 213 due to the energization of the first primary winding 201 and the second primary winding 202, and the winding loss is reduced. growing. As a result, the amount of heat generated becomes large, and it becomes a factor that hinders downsizing because it is necessary to adopt a structure that promotes heat dissipation.

  More specifically, in FIG. 8, a first primary winding 201, a third secondary winding 213, a fourth secondary winding 214, and a second secondary winding are provided below the first secondary winding 211. A primary winding 202 and a second secondary winding 212 are arranged. For example, when a current flows in the first direction indicated by the solid line in the first primary winding 201 and the second primary winding 202, the following occurs.

  A current flows through the upper surface and the lower surface of the first primary winding 201 and a current flows through the second primary winding 202. Then, a current flows through the lower surface of the first secondary winding 211 and the upper surface of the third secondary winding 213 facing the upper and lower surfaces of the first primary winding 201. Here, an eddy current is generated on the upper surface of the fourth secondary winding 214 under the influence of the magnetic field of the primary winding.

Similarly, when a current flows through the first primary winding 201 and the second primary winding 202 in the second direction indicated by the broken line, the following occurs.
A current flows through the first primary winding 201 and a current flows through the upper surface and the lower surface of the second primary winding 202. Then, a current flows through the upper surface of the second secondary winding 212 and the lower surface of the fourth secondary winding 214 facing the upper and lower surfaces of the second primary winding 202. Here, an eddy current is generated on the lower surface of the third secondary winding 213 under the influence of the magnetic field of the primary winding.

  In contrast, in the present embodiment, as shown in FIG. 1, the first primary winding 31, the fourth secondary winding 44, and the third secondary winding are provided below the first secondary winding 41. A winding 43, a second primary winding 32, and a second secondary winding 42 are arranged. For example, when a current flows through the first primary winding 31 and the second primary winding 32 in the first direction indicated by the solid line, the following occurs. A current flows on the upper surface of the first primary winding 31 and a current flows on the upper surface of the second primary winding 32. Then, a current flows on the lower surface of the first secondary winding 41 facing the upper surface of the first primary winding 31 and the third secondary winding faces the upper surface of the second primary winding 32. A current flows on the lower surface of 43. Therefore, no eddy current is generated.

  Similarly, when a current flows through the first primary winding 31 and the second primary winding 32 in the second direction indicated by the broken line, the following occurs. A current flows on the lower surface of the first primary winding 31 and a current flows on the lower surface of the second primary winding 32. A current flows on the upper surface of the fourth secondary winding 44 facing the lower surface of the first primary winding 31 and the second secondary winding faces the lower surface of the second primary winding 32. A current flows on the upper surface of 42. Therefore, no eddy current is generated.

  In this way, current flows in the reverse direction in the first secondary winding 41 and the third secondary winding 43 by energization of the primary winding 30, and the fourth secondary winding is energized by energization of the primary winding 30. A current flows in the opposite direction in the wire 44 and the second secondary winding 42. Therefore, eddy currents can be hardly formed, and winding loss can be reduced. As a result, the amount of heat generation is reduced, and it is not necessary to adopt a structure that promotes heat dissipation, so that downsizing can be achieved. Thus, in this embodiment, the secondary windings are arranged in parallel and the mutual arrangement of the secondary windings is devised. Therefore, winding loss can be reduced, and transformer (transformer) loss reduction and transformer (transformer) size reduction can be achieved.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the transformer 10, the core 20, the first primary winding 31 wound around the core 20, and the first primary winding 31 wound around the core 20 and connected in series to the first primary winding 31. Two primary windings 32, a first secondary winding 41 wound around the core 20, and a second secondary wound around the core 20 and connected in series to the first secondary winding 41 And winding 42. In addition, an intermediate tap 50 is provided between the first secondary winding 41 and the second secondary winding 42. Further, the third secondary winding 43 wound around the core 20 and connected in parallel to the first secondary winding 41 and the third secondary winding 43 wound around the core 20 and connected in parallel to the second secondary winding 42 are connected. And a fourth secondary winding 44. Further, the first primary winding 31 is disposed between the first secondary winding 41 and the fourth secondary winding 44, and the second secondary winding 42 and the third secondary winding 44 are arranged. A second primary winding 32 is arranged between the secondary winding 43. Further, the first secondary winding 41 and the first primary winding 31 overlap each other, and the first primary winding 31 and the fourth secondary winding 44 overlap each other. Yes. In addition, the fourth secondary winding 44 and the third secondary winding 43 overlap each other, and the third secondary winding 43 and the second primary winding 32 overlap each other. The second primary winding 32 and the second secondary winding 42 are adjacent to each other and overlap each other.

  As a result, when the first primary winding 31 and the second primary winding 32 are energized, the first secondary winding 41 and the third secondary winding 43 or the second secondary winding. Current flows through line 42 and fourth secondary winding 44. Therefore, there is no winding that obstructs the magnetic field generated by energization of the first primary winding 31 and the second primary winding 32, so that winding loss is reduced.

Moreover, since the 1st primary winding 31 and the 2nd secondary winding 42 can be piled up, a projection area can be reduced.
(2) When a current flows in the first direction with respect to the first primary winding 31 and the second primary winding 32, the current flows through the first secondary winding 41 and the third secondary winding 43. When a current flows in the second direction with respect to the first primary winding 31 and the second primary winding 32, a current flows through the second secondary winding 42 and the fourth secondary winding 44. Is provided on the primary side. A diode 71 as a first diode is connected to one end of the first secondary winding 41, and a diode 72 as a second diode is connected to one end of the second secondary winding 42. Therefore, a current can be passed through the first primary winding 31 and the second primary winding 32 in the first direction and the second direction.

The embodiment is not limited to the above, and may be embodied as follows, for example.
-It is good also as a structure shown in FIG. The primary winding 30 includes a first primary winding 31, a second primary winding 32, a third primary winding 33, and a fourth primary winding 34. The first primary winding 31, the second primary winding 32, the third primary winding 33, and the fourth primary winding 34 are connected in series. The first primary winding 31 and the second primary winding 32 are configured by alpha winding. The third primary winding 33 and the fourth primary winding 34 are configured by alpha winding. The secondary winding 40 includes a first secondary winding 41, a second secondary winding 42, a third secondary winding 43, a fourth secondary winding 44, and a fifth secondary winding. 45, a sixth secondary winding 46, a seventh secondary winding 47, and an eighth secondary winding 48. The first secondary winding 41 and the second secondary winding 42 are connected in series. A third secondary winding 43, a fifth secondary winding 45, and a seventh secondary winding 47 are connected in parallel to the first secondary winding 41. A fourth secondary winding 44, a sixth secondary winding 46, and an eighth secondary winding 48 are connected to the second secondary winding 42 in parallel. In the laminated structure of the windings 31, 32, 33, 34, 41, 42, 43, 44, 45, 46, 47, 48, the uppermost stage is the first secondary winding 41. Below that, the first primary winding 31, the fourth secondary winding 44, the third secondary winding 43, the second primary winding 32, and the second secondary winding 42 are sequentially provided. , Fifth secondary winding 45, third primary winding 33, eighth secondary winding 48, seventh secondary winding 47, fourth primary winding 34, sixth secondary winding. A line 46 is arranged.

In FIG. 1, the first primary winding 31 and the second primary winding 32 are configured by alpha winding, but may not be configured by alpha winding.
The number of turns of the first primary winding 31 is “7”, the number of turns of the second primary winding 32 is “7”, the number of turns of the first secondary winding 41 is “1”, and the second secondary winding. The number of turns of the wire 42 was “1”, the number of turns of the third secondary winding 43 was “1”, and the number of turns of the fourth secondary winding 44 was “1”. However, the number of turns of the winding is not limited to this.

-You may use for a step-up circuit instead of a step-down circuit.
・ Has a half-bridge configuration, but is not limited to this. For example, a full bridge configuration may be used. In addition, a push-pull type may be used.

-Although the core 20 used the EI type | mold core, it is not restricted to this. For example, an EE type core may be used.
-Although each coil | winding 31, 32, 41, 42, 43, 44 demonstrated planarly arrange | positioned and laminated | stacked, it has not restricted to this. For example, the windings 31, 32, 41, 42, 43, and 44 may be cylindrical, and the windings 31, 32, 41, 42, 43, and 44 may be arranged in the radial direction.

  Although diodes 71 and 72 are used on the secondary side of the transformer, this is not restrictive. For example, a rectifying element such as a switching element may be used.

  DESCRIPTION OF SYMBOLS 10 ... Transformer, 20 ... Core, 31 ... 1st primary winding, 32 ... 2nd primary winding, 41 ... 1st secondary winding, 42 ... 2nd secondary winding, 43 ... 1st 3 secondary windings, 44... Fourth secondary winding, 50... Intermediate tap, 60... Bridge circuit, 71.

Claims (3)

The core,
A first primary winding wound around the core;
A second primary winding wound around the core and connected in series with the first primary winding;
A first secondary winding wound around the core;
A second secondary winding wound around the core and connected in series to the first secondary winding;
An intermediate tap provided between the first secondary winding and the second secondary winding;
A third secondary winding wound around the core and connected in parallel to the first secondary winding;
A fourth secondary winding wound around the core and connected in parallel to the second secondary winding;
A transformer having
The first primary winding is disposed between the first secondary winding and the fourth secondary winding, and the second secondary winding and the third secondary winding are arranged. The second primary winding is arranged between the wire and
The first secondary winding and the first primary winding overlap each other, the first primary winding and the fourth secondary winding overlap each other, and the first 4 secondary winding and the third secondary winding are adjacent to each other, the third secondary winding and the second primary winding are adjacent to each other, and the second secondary winding A transformer, wherein the primary winding and the second secondary winding overlap each other. When a current flows in a first direction with respect to the first primary winding and the second primary winding, a current is passed through the first secondary winding and the third secondary winding; A bridge that allows current to flow through the second secondary winding and the fourth secondary winding when current flows in a second direction with respect to the first primary winding and the second primary winding. With the circuit on the primary side,
The first diode is connected to one end of the first secondary winding, and the second diode is connected to one end of the second secondary winding. The described transformer. It further has a heat dissipation member,
Between the first secondary winding and the first primary winding, between the first primary winding and the fourth secondary winding, the fourth secondary winding and the Between the third secondary winding, between the third secondary winding and the second primary winding, and between the second primary winding and the second secondary winding. The transformer according to claim 1 or 2, wherein is molded with resin.

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