TW201409503A - Side-wound type winding transformer and winding method thereof - Google Patents

Abstract

A side-wound type winding transformer and winding method thereof at least comprise: an upright parallel arranged left iron core and right iron core. At least a first winding set wound at left iron core and a second winding set wound at the right iron core. Another embodiment comprises an upright parallel arranged left iron core, middle iron core and right iron core. At least a first winding set wound at the middle iron core, and a second winding set wound at least one of the left or right iron cores. In another embodiment, a first winding set on the internal layer and a second winding set at the outer layer wound at the middle iron core and a second winding set wound at least on one of the left or right iron cores. The first winding set and the second winding set are arranged at different secondary side (first side or secondary side). A side-wound type transformer is constituted by a first winding set wound at one side of the iron core and the second winding set wound at another iron core which can realize a transformer with adjustable leakage inductance, excellent heat dissipation, space saving and copper loss as well as iron loss reduced same as electricity and efficiency promotion.

Description

Edge winding type winding transformer and winding method thereof

The invention relates to a winding transformer and a winding method thereof, in particular to a structure of a side winding type winding transformer and a winding method thereof.

For power converters (eg, computer power supplies or switched power supplies), how to increase power density, reduce size, and increase switching frequency (switching frequency) is a concern for designers of power converters. Increasing the switching frequency can reduce the size of, for example, transformers and filters, but switching losses can adversely affect high frequency operation. In order to reduce switching losses, resonant switching techniques have been proposed.

In general, an LLC resonant power converter includes a controller with a metal oxide semiconductor field effect transistor (MOSFET), an LLC resonant network, and a rectifier network. The controller alternately switches the two MOSFETs by means of pulse frequency modulation (PFM), and changes the operating frequency as the load changes, adjusting the output voltage Vout. The LLC resonant network includes two resonant inductors (Lr and Lm) and one resonant capacitor (Cr). The LLC resonant power converter features zero voltage switching (ZVS) and low voltage stress on the device, making it ideal for applications requiring high efficiency and high power supplies. With the wide application of LLC resonant power converters, the design of LLC transformers for LLC resonant power converters has received increasing attention. It is known that an LLC transformer applied to an LLC resonant power converter usually integrates the magnetic elements Lr and Lm in one transformer, and utilizes the leakage inductance (leakage inductance) of the transformer as Lr, and utilizes the magnetic inductance (magnetizing inductance) of the transformer. As Lm, the number of magnetic elements can be reduced.

Conventional winding transformers have a fixed core with a primary (also called once) and Secondary (also known as secondary) coil, the winding of the coil is usually the same core in the coaxial relationship between the primary coil and the secondary coil, one of which is located in the inner ring and the other is located in the outer ring, primary The coils of the secondary are electrically separated from each other and insulated from each other, and the winding transformer wound in this manner has a better coupling density between the primary coil and the secondary coil, and thus has a small leakage inductance. In general, the amount of magnetic inductance (magnetizing inductance) of LLC is 3 to 7 times the amount of leakage inductance (magnetic leakage inductance), and the leakage inductance value is usually required to be large. In other words, the LLC transformer is applied to the LLC resonant power converter. The coupling density between the primary side and the secondary side of the transformer should be reduced to achieve a large leakage inductance.

On the other hand, when the winding transformer of the inner and outer windings is used in operation, the coil located in the inner ring also has a problem that heat dissipation is not easy. Therefore, the LLC transformer designed for the LLC resonant power converter needs to focus on designing the leakage inductance and magnetic inductance of the transformer, and designing the winding method of the primary side and the secondary side of the transformer.

The invention provides a edge-wound winding transformer and a winding method thereof, which have the advantages of convenient adjustment of leakage inductance, good heat dissipation effect, space saving, copper loss and iron loss, and electrical and efficiency effects.

In order to achieve the above-mentioned effects, an embodiment of the winding method of the edge winding type winding transformer of the present invention comprises: preparing a left side iron core and a right side iron core which are juxtaposed in parallel; and winding at least one first winding a left core; a second winding is wound around the right core, the second winding and the first winding are respectively coils of different secondary sides; and an insulating layer is disposed between the first winding and the second winding .

An embodiment of the winding method of the present invention further includes: a second winding is disposed around the outer layer of the first winding of the left core, and an insulating layer is disposed between the first winding of the inner layer and the second winding of the outer layer. The second winding wound around the outer layer of the left core and the second winding wound around the right core may be in series or parallel relationship with each other.

In order to achieve the above-mentioned effects, an embodiment of the winding method of the edge-wound winding transformer of the present invention comprises: preparing a left side iron core, an intermediate iron core and a right iron core in an upright side by side; a first winding is disposed on the intermediate core; a second winding is disposed on at least one of the left iron core and the right iron core, the second winding and the first winding are respectively coils of different secondary sides; and setting An insulating layer is between the first winding and the second winding.

According to an embodiment of the above method of the present invention, wherein the left core and the right core are respectively wound with the second winding, the second windings wound around the left core and the right core may be in series or parallel relationship with each other.

According to an embodiment of the above method, the method further includes: a second winding is disposed around an outer layer of the first winding of the intermediate core, and the first winding of the inner layer and the second winding of the outer layer are disposed An insulating layer, wherein the left side core and the right side iron core are respectively wound around the second winding, and the second windings wound around the left side iron core, the middle iron core and the right side iron core may be connected in series with each other or Parallel relationship.

According to an embodiment of the above method, the method further includes: a second winding is disposed around an outer layer of the first winding of the intermediate core, and the first winding of the inner layer and the second winding of the outer layer are disposed An insulating layer, wherein the left iron core and the right iron core are respectively wound around the second winding, The second windings wound around the left core and the right core are connected in parallel with each other and then in series with the second winding wound around the intermediate core.

An embodiment of the edge wound winding transformer of the present invention comprises: at least two upright juxtaposed iron cores, and first and second windings respectively wound around the two upright juxtaposed iron cores, The first winding and the second winding are respectively coils of different secondary sides, and an insulating layer is disposed between the first winding and the second winding; and the side of one of the iron cores around which the first winding is wound is disposed The other core around which the second winding is wound constitutes a side-wound winding transformer, thereby achieving the aforementioned effects.

An embodiment of the edge-wound winding transformer of the present invention comprises: an upright side-by-side side iron core and a right side iron core, the left side iron core is provided with at least a first winding, and the right side iron core is wound with a second winding The first winding and the second winding are respectively coils of different secondary sides, and an insulating layer is disposed between the first winding and the second winding, and the first and second windings are any one of copper wire, copper foil or enameled wire.

Another embodiment of the edge wound winding transformer according to the present invention comprises: an upright side-by-side left core and a right core, the left core being wound with a first winding located in the inner layer and a second winding located in the outer layer The winding has a second winding wound around the right core. The first winding and the second winding are respectively coils of different secondary sides, and an insulating layer is disposed between the first winding and the second winding.

Another embodiment of the edge wound winding transformer according to the present invention comprises: three upright side-by-side side iron cores, an intermediate iron core and a right iron core, wherein the middle iron core is at least wound with the first winding, At least one of the left core and the right core is wound around a second winding, the first winding and the second winding being coils of different secondary sides, respectively, and an insulating layer is disposed between the first winding and the second winding.

Another embodiment of a edge wound winding transformer according to the present invention comprises: three straight a side iron core, a middle iron core and a right iron core which are juxtaposed, and the middle iron core is wound with a first winding located at the inner layer and a second winding located at the outer layer, and at least one of the left iron core and the right iron core is wound There is a second winding, the first winding and the second winding are respectively coils of different secondary sides, and an insulating layer is disposed between the first winding and the second winding.

An embodiment of the edge wound winding transformer according to the present invention, wherein the left iron core and the right iron core are respectively wound with the second winding, and the second windings wound around the left iron core and the right iron core may be each other The relationship of series or parallel.

An embodiment of the edge wound winding transformer according to the present invention, wherein the left iron core and the right iron core are respectively wound with a second winding, and are wound around the second iron core, the right iron core and the middle iron core. The windings are connected in series.

An embodiment of the edge wound winding transformer according to the present invention, wherein the left side core and the right side iron core are respectively wound with the second winding, and the second windings wound around the left side core and the right side core are connected in parallel with each other and then And in series with the second winding wound around the intermediate core.

According to the foregoing invention, it can be understood that the edge winding type winding transformer of the present invention forms a side winding type winding transformer by means of winding the first winding and the second winding respectively in at least two upright parallel iron cores. The basic construction, other embodiments based on this basic configuration, by means of three upright juxtaposed cores, and in which one of the cores is wound with a single layer coil or a double layer coil, thereby completing a The edge-wound winding transformer can achieve the following functions.

1. Using the edge-wound structure, it can reduce iron loss and copper loss, improve electrical and efficiency.

2. Using the side-wound construction, the same wire frame and core are more powerful than ordinary winding transformers.

3. Using the side-wound structure, there is a large airflow gap between the coils of the adjacent vertical juxtaposed cores, which can improve the heat dissipation effect of the transformer, reduce the loss, and improve the transformer. Utilization rate.

4. Using the side-wound configuration, it is possible to adjust the airflow gap between any two adjacent upright juxtaposed cores, and has the effect of conveniently adjusting the leakage inductance.

5. Using the edge-wound configuration, the inductance and leakage inductance can be integrated into one, which saves space occupied by the circuit when applied to the LLC transformer.

The details of other functions and embodiments of the present invention will be described below in conjunction with the drawings.

An embodiment of the winding method of the edge winding type winding transformer of the present invention, as shown in FIG. 1 , includes: preparing a left side iron core and a right side iron core which are juxtaposed in parallel; and winding at least one first Winding on the left side iron core; winding a second winding on the right side iron core, the second winding and the first winding are respectively different secondary side coils; and providing an insulating layer in the first winding and the second Between the windings.

According to an embodiment of the above method, an embodiment of the edge wound winding transformer of the present invention is constructed as shown in FIG. 2, and includes: an upright side-by-side left core 10L and a right core 10R, and a left iron The core 10L is wound around at least the first winding C1, and the right core 10R is wound around the second winding C2. The first winding C1 and the second winding C2 are respectively different secondary (primary or secondary) coils. An insulating layer 20 is disposed between the one winding C1 and the second winding C2.

An embodiment of the winding method of the present invention further includes winding a second winding C2 around the outer layer of the first winding C1 of the left core 10L, the first winding C1 of the inner layer and the second winding C2 of the outer layer. An insulating layer 20 is disposed between the second winding C2 and the winding around the outer layer of the left core 10L. The second windings C2 provided on the right side core 10R may be in a series or parallel relationship with each other.

According to an embodiment of the above method, another embodiment of the edge wound winding transformer of the present invention, as shown in FIG. 3, comprises: an upright side-by-side left core 10L and a right core 10R, and a left iron The core 10L is wound with a first winding C1 located in the inner layer and a second winding C2 located at the outer layer, and the right core 10R is wound around the second winding C2, and the first winding C1 and the second winding C2 are respectively coils of different secondary sides. (primary or secondary side), an insulating layer 20 is provided between the first winding C1 and the second winding C2, in other words, if the first winding C1 is the primary side coil of the winding transformer, the second winding C2 is the winding The secondary side coil of the transformer and vice versa.

Another embodiment step of the winding method of the edge-wound winding transformer of the present invention, such as "figure 4", includes: preparing a left side iron core, an intermediate iron core and a right iron core which are juxtaposed in parallel; a first winding is disposed on the intermediate core; a second winding is disposed on at least one of the left iron core and the right iron core, and the second winding and the first winding are respectively coils of different secondary sides; An insulating layer is disposed between the first winding and the second winding.

According to an embodiment of the above method of the present invention, wherein the left core and the right core are respectively wound with the second winding, the second windings wound around the left core and the right core may be in series or parallel relationship with each other.

According to an embodiment of the above method, the method further includes: a second winding is disposed around an outer layer of the first winding of the intermediate core, and the first winding of the inner layer and the second winding of the outer layer are disposed An insulating layer, wherein the left iron core and the right iron core are respectively wound around the second winding, and the second winding wound around the left iron core, the middle iron core and the right iron core may be a string of each other The relationship of joint or parallel.

According to an embodiment of the above method, the method further includes: a second winding is disposed around an outer layer of the first winding of the intermediate core, and the first winding of the inner layer and the second winding of the outer layer are disposed An insulating layer, wherein the left iron core and the right iron core are respectively wound around the second winding, and the second windings wound around the left iron core and the right iron core are connected in parallel with each other and then disposed in the middle The second winding of the iron core is connected in series.

According to the embodiment of the above method, another embodiment of the edge-wound winding transformer according to the present invention is constructed as shown in FIG. 5, comprising: three vertically aligned left iron cores 10L and intermediate iron cores 10C. And the right iron core 10R, the intermediate iron core 10C is disposed at least around the first winding C1, and at least one of the left iron core 10L and the right iron core 10R is wound around the second winding C2. In other words, one embodiment is only The left core 10L is wound around the second winding C2. In another embodiment, the second winding C2 is wound only on the right core 10R. In another embodiment, the second core 10L and the right core 10R are wound around the second. Winding (see "figure 5"), the first winding C1 and the second winding C2 are respectively different secondary windings (primary or secondary), and insulation is provided between the first winding C1 and the second winding C2 The layer 20, the first winding C1 or the second winding C2 may be any one of copper wire, copper foil or enameled wire.

Another embodiment of the edge wound winding transformer according to the present invention, as shown in FIG. 6, includes: three vertically aligned left iron cores 10L, an intermediate iron core 10C, and a right iron core 10R. The iron core 10C is wound with a first winding C1 located at the inner layer and a second winding C2 at the outer layer, and at least one of the left side core 10L and the right side core 10R is wound around the second winding C2, in other words, one of them The embodiment only winds the second winding C2 on the left core 10L, and the other embodiment only winds the second winding C2 on the right core 10R, and the other embodiment is on the left core 10L and the right iron. The core 10R is wound around a second winding (see "Fig. 6"), and the first winding C1 and the second winding C2 are respectively coils of different secondary sides, and insulation is provided between the first winding C1 and the second winding C2. Layer 20, that is, if the first winding C1 is the primary side winding of the winding transformer, the second winding C2 is the secondary side winding of the winding transformer and vice versa.

The first winding C1 and the second winding C2 may be any one of copper wire, copper foil or enamel wire; the first winding C1 and the second winding C2 are respectively different secondary windings, in other words, the first winding C1 Is the primary side coil of the winding transformer, and the second winding C2 is the secondary side coil of the winding transformer. Basically, the number of turns of the first winding C1 and the second winding C2 can be determined according to the specification and output power of the transformer, and The number of layers in which a coil is wound around any of the cores is not limited to a single layer, and may be a single layer or a multilayer structure depending on the specifications of the transformer.

The foregoing insulating layer 20 between the first winding C1 and the second winding C2 may be an insulating tape or an insulating member made of other insulating materials, which will be described in detail below in conjunction with the embodiments.

The edge-wound winding transformer proposed by the invention can integrate the inductance and the leakage inductance, and can save the space occupied by the circuit when applied to the LLC transformer. On the other hand, the edge-wound winding transformer proposed by the invention In an embodiment having three upright side-by-side iron cores 10L, an intermediate core 10C and a right core 10R, the second winding C2 can also be used in conjunction with an LLC transformer in the circuit design of the LLC resonant power converter. Different ways of electrical connection in series or in parallel are described below.

In an embodiment having three vertically aligned left iron cores 10L, intermediate iron cores 10C and right iron cores 10R, an electrical connection manner of the second windings C2 is as shown in the equivalent circuit diagram of "FIG. 7-1". Shown in which the second winding C2 wound around the left iron core 10L and the right iron core 10R is in contact with each other The series connection is another embodiment of the electrical connection, as shown in the equivalent circuit diagram of "No. 7-2", in which the second winding C2 wound around the left core 10L and the right core 10R are connected in parallel with each other.

In the embodiment having three upright side-by-side left cores 10L, intermediate cores 10C and right cores 10R, when the intermediate core 10C is wound with the first winding C1 located in the inner layer and the second winding C2 located in the outer layer An electrical connection manner of the second winding C2 is as shown in the equivalent circuit diagram of "No. 7-3", and the second winding C2 wound around the left iron core 10L, the right iron core 10R, and the intermediate iron core 10C is mutually In series, another electrical connection is implemented, for example, as shown in the equivalent circuit diagram of FIG. 7-4, in which the second winding C2 wound around the left iron core 10L and the right iron core 10R is connected in parallel with each other and then wound. The second winding C2 of the intermediate core 10C is connected in series.

According to the edge winding type winding transformer of the present invention, an embodiment in which three vertical side cores 10L, an intermediate core 10C and a right core 10R are juxtaposed therein is exemplified, and a specific one will be disclosed below with reference to the drawings. The structural examples are explained below.

A side-wound winding transformer as shown in Fig. 8 includes: two butted E-shaped cores 30A and 30B. The core material can be made of oxyiron material, and two E-types are connected through the docking. The iron cores 30A and 30B constitute a structure having three vertically aligned left iron cores 10L, intermediate iron cores 10C and right iron cores 10R, but not limited to such E-shaped iron cores, and other types such as type I, type T or U-shaped iron core can also be used.

A winding seat, which is a plastic molding component, can be used as the above-mentioned insulator 20. The winding seat comprises: a left winding frame 40L, an intermediate winding frame 40C and a right winding frame 40R, a left winding frame 40L, and an intermediate winding. The frame 40C and the right bobbin 40R are both tubular type components which can be respectively sleeved on the outer periphery of the left side iron core 10L, the intermediate iron core 10C and the right iron core 10R, and can be combined with the E-shaped iron cores 30A and 30B. The main structure of the wound winding transformer (see "Figure 9"), which is left The side bobbin 40L, the intermediate bobbin 40C and the right bobbin 40R may define a winding space for the first winding C1 and the second winding C2 to be wound, and the top end of the intermediate bobbin 40C is extended on both sides. A face 41 is provided to prevent the first winding C1 and/or the second winding C2 from coming out, and a plurality of terminal pins 42 are provided on both sides of the bottom end of the intermediate bobbin 40C, and the first winding C1 and the second winding are additionally provided. Between C2, an insulating layer 20 (using an insulating tape) may be provided, and finally a layer 20 (using an insulating tape) may be applied to the periphery of the edge-wound winding transformer, which may become a type 10 The structure shown in the figure.

While the present invention has been described above by way of example, the present invention is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of patent protection is subject to the terms of the claims attached to this specification.

10C‧‧‧ intermediate core

10L‧‧‧left core

10R‧‧‧right core

20‧‧‧Insulation

30A‧‧‧E core

30B‧‧‧E core

40L‧‧‧left winding frame

40C‧‧‧Intermediate Winding Rack

40R‧‧‧Right bobbin

41‧‧‧檐

42‧‧‧Wiring pins

C1‧‧‧First winding

C2‧‧‧second winding

Fig. 1 is a view showing an embodiment of a winding method of a side winding type winding transformer of the present invention.

Fig. 2 is a schematic view showing the construction of two vertical iron cores, a right iron core, a first winding and a second winding which are juxtaposed in parallel according to an embodiment of the present invention.

3 is an embodiment of the present invention, showing a schematic structural view of two vertically aligned left iron cores, a right iron core, a first winding, and a second winding, wherein the inner layer of the left core is the outer layer of the first winding Second winding.

Fig. 4 is a view showing another embodiment of the winding method of the edge wound type winding transformer of the present invention.

Fig. 5 is a schematic view showing the configuration of three vertically aligned left iron cores, intermediate iron cores, right iron cores, first windings and second windings in an embodiment of the present invention.

Figure 6 is a schematic view showing the structure of three vertically aligned left iron cores, intermediate iron cores, right iron cores, first windings and second windings, the inner layer of the middle iron core being the first The outer layer of the winding is a second winding.

7-1 to 7-2 are an embodiment of the present invention, shown in an embodiment having three upright juxtaposed iron cores, respectively wound around a second winding of a left core and a right core An equivalent circuit diagram.

7-3 to 7-4 are an embodiment of the present invention, shown in an embodiment having three upright juxtaposed iron cores, respectively wound around a left core, an intermediate core, and a right core. An equivalent circuit diagram of the second winding.

Fig. 8 is a view showing an embodiment of the present invention showing the shape of an element for composing three upright juxtaposed iron cores and a combination thereof.

Figure 9 is a combination diagram of the construction of the embodiment of Figure 8, showing the composition of three upright juxtapositions The construction of the components of the iron core is completed.

Fig. 10 is a view showing the construction of an embodiment of the present invention, showing the appearance of the package in which the iron core of Fig. 8 is completed after winding the coil.

10C‧‧‧ intermediate core

10L‧‧‧left core

10R‧‧‧right core

30A‧‧‧E core

30B‧‧‧E core

40L‧‧‧left winding frame

40C‧‧‧Intermediate Winding Rack

40R‧‧‧Right bobbin

41‧‧‧檐

42‧‧‧Wiring pins

Claims (22)

A winding method of a side winding type winding transformer, comprising: preparing a left side iron core and a right side iron core which are juxtaposed in parallel; winding at least one first winding on the left side iron core; and winding a second winding on the a right core, the second winding and the first winding are respectively coils of different secondary sides; and an insulating layer is disposed between the first winding and the second winding. The winding method of the edge wound winding transformer according to claim 1, further comprising: winding a second winding on the outer layer of the first winding of the left iron core, the first winding of the inner layer An insulating layer is disposed between the second winding of the outer layer, and the second winding wound around the outer layer of the left core and the second winding wound around the right core are connected in series with each other. The winding method of the edge wound winding transformer according to claim 1, further comprising: winding a second winding on the outer layer of the first winding of the left iron core, the first winding of the inner layer An insulating layer is disposed between the second winding of the outer layer, and the second winding wound around the outer layer of the left core and the second winding wound around the right core are connected in parallel with each other. The winding method of the winding type winding transformer according to claim 1, wherein the left iron core and the right iron core may be any one of an E type, an I type, a T type, and a U type iron core. . The winding method of the edge wound winding transformer according to claim 1, wherein the first winding or the second winding is any one of a copper wire, a copper foil or an enameled wire. A winding method of a side winding type winding transformer, comprising: preparing a left side iron core, an intermediate iron core and a right iron core arranged in parallel; and winding at least one first winding on the middle iron core; Winding a second winding on at least one of the left side core and the right side core, the second winding and the first winding are respectively different secondary side coils; and providing an insulating layer in the first winding and Between the second windings. The winding method of the winding-wound type winding transformer according to claim 6, wherein the left iron core and the right iron core are respectively wound around the second winding, and are disposed around the left iron core and the right side. The second windings of the iron core are connected in series with each other. The winding method of the winding-wound type winding transformer according to claim 6, wherein the left iron core and the right iron core are respectively wound around the second winding, and are disposed around the left iron core and the right side. The second windings of the iron core are connected in parallel with each other. The winding method of the edge wound winding transformer according to claim 6, further comprising: winding a second winding on the outer layer of the first winding of the intermediate core, the first winding of the inner layer And an insulating layer is disposed between the second winding of the outer layer, wherein the left side core and the right side iron core are respectively disposed around the second winding, and the left side iron core, the middle iron core and the right side iron are wound around The second windings of the core are connected in series with each other. The winding method of the edge wound winding transformer according to claim 6, further comprising: winding a second winding on the outer layer of the first winding of the intermediate core, the first winding of the inner layer And an insulating layer is disposed between the second winding of the outer layer, wherein the left side core and the right side iron core are respectively disposed around the second winding, and the left side iron core, the middle iron core and the right side iron are wound around The second windings of the core are connected in parallel with each other. The winding method of the edge wound winding transformer according to claim 6, further comprising: winding a second winding on the outer layer of the first winding of the intermediate core, the first winding of the inner layer And an insulating layer is disposed between the second winding of the outer layer, wherein the left side core and the right side The iron cores are respectively wound around the second winding, and the second windings wound around the left side iron core and the right side iron core are connected in parallel with each other and then connected in series with the second winding wound around the intermediate iron core. An edge wound winding transformer comprising: at least two upright juxtaposed iron cores; and a first winding and a second winding respectively wound around the two upright juxtaposed iron cores, the first winding and the first winding The second windings are respectively coils of different secondary sides, and an insulating layer is disposed between the first winding and the second winding. The edge wound winding transformer of claim 12, wherein one of the two upright juxtaposed iron cores is provided with the first winding located in the inner layer and the second inner layer The winding, the other core is wound around the second winding, and the first winding and the second winding are respectively coils of different secondary sides. The edge-wound winding transformer according to claim 12, wherein the iron cores are erected in parallel, comprising: a left iron core, an intermediate iron core and a right iron core, the middle The iron core is at least wound around the first winding, and the second winding is wound around at least one of the left iron core and the right iron core. The side winding type winding transformer according to claim 13, wherein the left side iron core and the right side iron core are respectively wound around the second winding, and are disposed around the left side iron core and the right side iron core. The second windings are connected in series to each other. The edge-wound winding transformer according to claim 14, wherein the left iron core and the right iron core are respectively wound around the second winding, and are disposed around the left iron core and the right iron core. The second windings are connected in parallel with each other. The edge-wound winding transformer according to claim 14, wherein the left iron core and the right iron core are respectively wound around the second winding, and the intermediate iron core is disposed around the inner layer. A first winding and a second winding on the outer layer are provided with an insulating layer between the first winding of the inner layer and the second winding of the outer layer. A side winding type winding transformer according to claim 17, wherein the second winding wound around the left side core, the right side core, and the intermediate core are connected in series to each other. The side winding type winding transformer according to claim 17, wherein the second winding wound around the left iron core and the right iron core are connected in parallel with each other and then wound around the intermediate iron core. The second winding is connected in series. The side winding type winding transformer according to claim 12, wherein the iron cores are any one of an E type, an I type, a T type, and a U type iron core. The edge wound winding transformer of claim 12, wherein the insulating layer is an insulating tape or an insulating member made of other insulating materials. The edge wound winding transformer of claim 12, wherein the first winding or the second winding is any one of a copper wire, a copper foil or an enameled wire.