JP2000260640A - Output transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve magnetic couplings between primary and secondary windings and between the secondary windings. SOLUTION: The output transformer for use in a switching regulator power supply device having a primary winding P and a plurality of secondary windings S1 and S2 thereto, includes a bobbin 2. The bobbin has a core 1 mounted in a central axis direction and has a 5-layer structure of coil winding parts 2a to 2d formed in a core axis direction. With respect to the secondary winding S2 wound around central one 2c of the 5-layer coil winding parts 2a to 2d of the bobbin 2, the other primary and secondary windings P and S1 are symmetrically wound as divided and as sandwiched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output transformer used in a switching regulator power supply having a plurality of secondary windings for a primary winding.

[0002]

2. Description of the Related Art Conventionally, as an output transformer used in this type of switching regulator power supply, for example, there is one shown in FIG.

FIG. 8 shows an output transformer using a divided bobbin. In order to cope with a multi-output secondary winding, a core 1 is used.
Is used as a bobbin 101 having a three-layer structure and formed by dividing the three-layer coil winding portions 101a, 101b, and 101c in the core axis direction.

A three-layer bobbin 101 is wound with a primary winding P and two secondary windings S1 and S2. The primary winding P includes coil winding portions 101a, 101 at both ends of the bobbin 101.
01c, and the secondary windings S1 and S2 are separately wound around the center and outside in the center coil winding portion 101b.

[0005]

When the number of turns of the two secondary windings S1 and S2 is substantially equal, bifilar winding, which is known as a method of winding two or more wires at the same time, is performed. The magnetic coupling between the lines S1 and S2 can be improved. However, if the number of turns of the secondary windings S1 and S2 is significantly different, bifilar winding cannot be performed.
As described above, the secondary winding S1 winds the secondary winding S2.

Therefore, the magnetic coupling between the primary winding P and the secondary winding S1, the magnetic coupling between the primary winding P and the secondary winding S2,
Further, there is a problem that magnetic coupling between the secondary windings S1 and S2 is deteriorated, and characteristics as an output transformer are deteriorated.

[0007] Therefore, as shown in FIG.
By using the four-layer bobbin 102 formed with the two coil winding portions 102a to 102d, the secondary windings S1, S2
The secondary windings S1 and S2 are individually wound between the primary windings P located outside in a sandwich structure to improve the magnetic coupling between the primary winding P and the secondary windings S1 and S2.

However, even with the use of the four-layer bobbin, there is a problem that magnetic coupling is inevitably worse than that of a single-layer output transformer having one secondary winding.

The present invention has been made to solve the above-mentioned conventional problems and to provide an output transformer which further improves the magnetic coupling between the primary winding and the secondary winding, and furthermore between the secondary windings. Aim.

[0010]

In order to achieve this object, the present invention is configured as follows. The present invention relates to an output transformer used for a switching regulator power supply device having a plurality of secondary windings with respect to a primary winding, wherein a core is mounted in a central axis direction, and a coil winding portion is provided in a core axial direction. Is divided into a five-layer structure, and a winding wound around the center of a five-layer coil winding portion formed on a bobbin is divided into other windings and wound into a symmetric sandwich structure. It has a line structure.

As described above, the output transformer according to the present invention forms a bobbin having a five-layer structure to form a primary winding and / or a secondary winding.
By symmetrically dividing in the core axis direction and winding in a sandwich structure, the magnetic coupling between the primary winding and a plurality of secondary windings and the magnetic coupling between the secondary windings are improved. The connection of lines can be improved.

Further, by increasing the area where the primary winding and the secondary winding are wound side by side, an increase in winding resistance in a high frequency region due to the proximity effect can be reduced, and the temperature of the output transformer can be reduced. The rise can be reduced and the power supply efficiency can be improved.

When two secondary windings are used, the winding structure for the five-layer bobbin is such that the primary winding is divided into coil winding portions at both ends of the hobbin and wound into a sandwich structure, and the coil windings at both ends are wound. In each of the coil winding parts located inside the attachment part,
A plurality of secondary windings are divided and wound into a sandwich structure, and the remaining secondary winding is wound around a central winding portion.

When the number of secondary windings is two, the winding structure for the five-layer bobbin is such that one of the secondary windings is divided into coil winding portions at both ends of the hobbin and wound into a sandwich structure, and the coil at both ends is wound. The other of the secondary windings is divided into each of the coil winding portions located inside the winding portion and wound into a sandwich structure,
The primary winding is wound around the center winding part.

When the number of the secondary windings is three, the winding structure of the five-layer bobbin is such that the primary winding is divided into coil winding portions at both ends of the hobbin and wound into a sandwich structure, and the coil windings at both ends are wound. One secondary winding is divided into each of the coil winding portions located inside the portion and wound into a sandwich structure, and the remaining two secondary windings are bifilar wound around the center winding portion.

When the number of secondary windings is three, the winding structure of the five-layer bobbin is such that the primary winding is divided into coil winding portions at both ends of the hobbin and wound into a sandwich structure, and the coil windings at both ends are wound. Each of the coil windings located inside the
The secondary winding is split and bifilar wound into a sandwich structure, and the remaining secondary winding is wound around the central winding.

[0017]

FIG. 1 is an explanatory diagram of a first embodiment of an output transformer according to the present invention. In the output transformer of FIG. 1, a five-layer bobbin 2 in which a rod-shaped core 1 is arranged in the central axis direction is used.
5 coil winding portions 2a, 2 on the outer circumference along the axial direction of
b, 2c, 2d and 2e are formed.

The coil winding portion 2a of the five-layer bobbin 2
2e have two outputs V01, V01 with respect to the input Vi in FIG.
Taking a switching regulator power supply device using a single-inverter having multiple outputs that output the output signal 02 as an example, the output transformer Tf according to the present invention has two primary transformers P
It has the next windings S1 and S2.

In the single inverter shown in FIG. 2, a switching element 3 such as a MOSFET or a transistor is connected in series to the primary winding P, and the switching element 3 is controlled by the switching control section 4 so that the outputs V01 and V02 have a constant voltage. It turns on and off in response to a switching pulse whose pulse width is controlled.

A rectifier diode D1 and an output smoothing capacitor C1 are connected to the secondary winding S1 of the output transformer Tf. Similarly, a rectifier diode D2 and an output smoothing capacitor C2 are connected to the secondary winding S2.

When an output transformer Tf having two secondary windings S1 and S2 for such a primary winding P is constructed,
In the first embodiment shown in FIG. 1, the primary winding P is divided into two parts and wound around upper and lower coil winding parts 2a and 2e which are both ends of the five-layer bobbin 2. That is, for example, half of the number of turns is wound around the upper coil winding portion 2a of the primary winding P, and then the other half is wound around the lowermost coil winding portion 2e. As a result, the primary winding P is wound in a sandwich structure sandwiching the three coil winding portions 2b, 2c and 2d present on the inside from both sides.

The coil winding portions 2b, 2 inside the coil winding portions 2a, 2e at both ends located above and below the primary winding P.
The secondary winding S1 is divided and wound around d, and wound in a sandwich structure sandwiching the coil winding portion 2c located at the center. Then, the remaining secondary winding S2 is wound around the center coil winding portion 2c.

The output transformer according to the present invention using the five-layer bobbin 2 shown in FIG. 1 as compared with the conventional output transformer using the four-layer bobbin 102 shown in FIG.
The sandwich structure of the primary windings P located at both upper and lower ends by the division winding is the same, but among the secondary windings S1 and S2 wound therebetween, in the present invention, the secondary winding S1 is used. Can be divided into two and sandwiched by another secondary winding S2 located therebetween, and the secondary winding S1 is divided into two and wound, and the primary windings P and 2 are formed. The magnetic coupling between the secondary winding S1 and the magnetic coupling between the secondary windings S1 and S2 can be improved.

FIG. 3 is an explanatory view of a second embodiment of the output transformer of the present invention using the five-layer bobbin 2. In the second embodiment, the core 1 and the five-layer bobbin 2
1 is the same as that of the first embodiment shown in FIG. 1 except that the output transformer Tf of the single inverter shown in FIG. 2 has two secondary windings S1 and S2 for the primary winding P and a five-layer bobbin 2 The primary winding P is wound around the coil winding portion 2c at the center, and the secondary windings S1 and S2 are divided and wound at two symmetrical positions vertically about the primary winding P.

That is, the secondary winding S1 is wound in two on each of the coil winding portions 2b and 2d located on both sides of the primary winding P, and the remaining secondary winding S2 is vertically wound. Each of the outermost coil winding portions 2a and 2e positioned is divided into two and wound. For this reason, the two secondary windings S1 and S2 are provided for the primary winding P wound around the center coil winding portion 2c.
2 has a sandwich structure in which it is divided into two and positioned vertically.

In the second embodiment shown in FIG. 3, two secondary windings S located above and below the central primary winding P are also provided.
1 and S2 have a sandwich structure in which each of them is divided into two and wound, so that the primary winding P and the secondary windings S1 and S
2, and the magnetic coupling between the secondary windings S1 and S2 can be improved.

FIG. 4 is an explanatory diagram of a third embodiment of the output transformer of the present invention using the five-layer bobbin 2. The output transformer of the third embodiment has an output transformer Tf of 1 according to the present invention used for a single inverter as shown in FIG.
Three secondary windings S1, S2, S3 are provided for the secondary winding P, and among them, a transformer structure in which the number of turns of the secondary windings S2, S3 is almost the same is intended.

In the third embodiment shown in FIG. 4, the core 1 and the five-layer bobbin 2 are the same as those in the first embodiment shown in FIG. 1, but three secondary windings S1 to S3 as shown in FIG. The difference is that it is wound together with the next winding P. First, a five-layer bobbin 2
The coil winding portions 2a and 2e at both ends located above and below
By winding the next winding P in two parts, a sandwich structure is adopted for the winding positioned between the two windings.

The coil winding portions 2b, 2b inside the coil winding portions 2a, 2e in which the primary winding P is wound in a sandwich structure.
In 2d, one secondary winding S1 of the three secondary windings is divided into two and wound, thereby forming a sandwich structure with respect to the coil winding portion 2c located therebetween. Further, the central coil winding portion 2c is a bifilar winding in which two secondary windings S2 and S3 having substantially the same number of turns are wound simultaneously.

As described above, for the five coil winding portions 2a to 2e of the five-layer structure bobbin 2, the secondary winding of the primary winding and the three secondary windings of the output transformer shown in FIG. The primary winding P and the secondary winding S1 of the sandwich structure are obtained by forming a sandwich structure in which S1 is vertically symmetrically wound and the remaining secondary windings S2 and S3 are bifilar wound in the center.
And the magnetic coupling between the secondary winding S1 and the two secondary windings S2 and S3 wound by bifilar winding can be improved.

The single inverter of FIG. 5 differs from the single inverter of FIG. 2 in that a secondary winding S1, a rectifier diode D3 and an output smoothing capacitor C3 are newly added to the secondary side of the output transformer Tf. And different.

FIG. 6 is an explanatory diagram of a fourth embodiment of the present invention for an output transformer Tf provided with the three secondary windings S1 to S3 of FIG. In the output transformer according to the fourth embodiment, the primary winding P and the secondary winding S1 shown in FIG. 5 for the coil winding portions 2a to 2e of the five-layer bobbin 2 in which the core 1 is arranged in the central axis direction. The winding structure of S3 is the same as that of the third embodiment shown in FIG. 4 in that the primary winding P is divided at both upper and lower ends and wound in a sandwich structure, but the coil winding positioned inside the third embodiment is wound inside. Regarding the portions 2b and 2d, first, the two secondary windings S2 and S3 having substantially the same number of turns are divided into two to form bifilar winding, and the remaining secondary winding S1 is wound around the central coil winding portion 2c. ing.

Even in the output transformer for multi-output winding of the primary winding and three secondary windings shown in FIG. 6, the primary winding P and the secondary windings S2 and S3 wound by bifilar winding. The primary winding P and the secondary windings S2, S
3 and the magnetic coupling between the secondary windings S1, S3 and S1 can be improved.

In the third and fourth embodiments shown in FIGS. 4 and 6, three output windings S1 to S3 are connected to the five-layer bobbin 2.
, If the number of turns is substantially the same, the secondary windings S1, S
It is needless to say that a bifilar winding of the secondary winding S2 and a single winding of the secondary winding S3, or a bifilar winding of the secondary windings S1 and S3 and a single winding of the secondary winding S2 may be used.

Further, in the above embodiment, the case where the secondary windings S1 and S2 or the secondary windings S1 to S3 are provided for the primary winding P is taken as an example. If another winding that does not require much magnetic coupling is required for the winding, such a winding is replaced by the primary winding P or the secondary windings S1, S2 or S1 to S3 in each embodiment. You may make it wind inside or outside.

FIG. 7 is a circuit diagram of a switching regulator power supply device using two secondary windings. The output transformer of the present invention according to the first embodiment shown in FIG. 1 or the second embodiment shown in FIG. To form a half-bridge type inverter.

In the half-bridge inverter shown in FIG. 7, the output transformer Tref has a primary winding P and two secondary windings S1 and S2 with respect to the core.
1, S2 has an intermediate tap. For the primary winding P, the input Vi is divided into two power supplies by capacitors C3 and C4,
Switch elements 3a and 3b are provided for each power supply. The switching control unit 4 is provided for the switching elements 3a and 3b.
a, 4b are provided, and the control pulses required by the switching control units 4a, 4b are different in phase by 180 °.
The secondary windings S1 and S2 of the output transformer Tf are commonly connected from both sides to the intermediate tap via rectifier diodes D11 and D12, and an output smoothing capacitor C1 is provided following the choke coil L1. Similarly, also for the secondary winding S2, rectifier diodes D21 and D22 are inserted into lines from both ends with respect to the intermediate tap, their outputs are connected in common, and a load-side output smoothing capacitor C2 is provided via a choke coil L2.

Further, the output transformer of the present invention can be applied to a push-pull type inverter. Since the push-pull type inverter has two primary windings, FIGS. In the sixth embodiment, the primary winding P may be a bifilar winding.

The present invention is not limited to the above-described embodiment, but can be applied to any output transformer having multiple outputs by providing two or more secondary windings for the primary winding.

[0040]

As described above, according to the present invention, a bobbin having a five-layer structure is formed to form a primary winding and / or a secondary winding.
By winding the secondary winding symmetrically in the core axis direction and winding it in a sandwich structure, the magnetic coupling between the primary winding and multiple secondary windings and the magnetic coupling between the secondary windings are improved. Can be done.

Further, since the area where the primary winding and the secondary winding are wound side by side on the five-layer structure bobbin is increased, it is possible to suppress the rise of the winding resistance in the high frequency region due to the proximity effect. As a result, the temperature rise of the output transformer can be reduced and the power supply efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a first embodiment of the present invention in which two secondary windings are wound around a five-layer bobbin.

FIG. 2 is a circuit diagram of a single inverter using the output transformer of FIG.

FIG. 3 is an explanatory view of a second embodiment of the present invention in which two secondary windings are wound around a five-layer bobbin.

FIG. 4 is an explanatory view of a third embodiment of the present invention in which three secondary windings are wound around a five-layer bobbin.

FIG. 5 is a circuit diagram of a single inverter using the output transformer of FIG.

FIG. 6 is an explanatory view of a fourth embodiment of the present invention in which three secondary windings are wound around a five-layer bobbin.

FIG. 7 is a circuit diagram of a half-bridge inverter using the output transformer of FIG. 1;

FIG. 8 is an explanatory diagram of a conventional output transformer using a three-layer bobbin.

FIG. 9 is an explanatory diagram of an output transformer using a conventional four-layer bobbin.

[Explanation of symbols]

 1: Core 2: Five-layer bobbin 2a to 2d: Coil winding part 3, 3a, 3b: Switch element , 4a, 4b: switching controller P: primary winding S1, S2, S3: secondary winding

Claims (5)

[Claims] 1. An output transformer for use in a switching regulator power supply device having a plurality of secondary windings for a primary winding, wherein a core is mounted in a center axis direction and a coil is wound in a core axis direction. And a winding structure formed by dividing a winding into a symmetric sandwich structure with respect to a winding wound around the center of the coil winding portion having the five-layer structure. And an output transformer. 2. The output transformer according to claim 1, wherein when the number of the secondary windings is two, the winding structure divides the primary winding into coil winding portions at both ends of the hobbin. And wound into a sandwich structure, the plurality of secondary windings are divided into each of the coil winding portions located inside the coil winding portions at both ends, and wound into a sandwich structure, and left in the center winding portion. An output transformer characterized by winding the secondary winding of the above. 3. The output transformer according to claim 1, wherein when the number of the secondary windings is two, the winding structure includes one of the secondary windings at coil winding portions at both ends of the hobbin. Is wound into a sandwich structure, and the other of the secondary windings is divided and wound into a sandwich structure at each of the coil winding portions located inside the coil winding portions at both ends, and a center winding portion is formed. An output transformer, wherein the primary winding is wound. 4. The output transformer according to claim 1, wherein when the number of the secondary windings is three, the winding structure divides the primary winding into coil winding portions at both ends of the hobbin. And wound into a sandwich structure, one secondary winding is divided into each of the coil winding portions located inside the coil winding portions at both ends and wound into a sandwich structure, and the remaining winding is wound around the center winding portion. An output transformer wherein two secondary windings are wound by bifilar. 5. The output transformer according to claim 1, wherein when the number of the secondary windings is three, the winding structure divides the primary winding into coil winding portions at both ends of the hobbin. Then, the two secondary windings are divided into each of the coil winding portions located inside the coil winding portions at both ends, and bifilar winding is performed on the sandwich structure. An output transformer characterized by winding one remaining secondary winding.