JP3057203B2 - Print coil type transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer used for an electronic device or a power supply device, and more particularly to an improvement in a stacking order of a multilayer printed coil type transformer.

[0002]

2. Description of the Related Art A transformer having laminated windings is disclosed, for example, in Japanese Utility Model Laid-Open No. 4-46524 proposed by the present applicant. FIG. 4 is a configuration diagram of such a conventional apparatus.
In the figure, a terminal 1-1 of a primary winding n1 of a transformer is grounded to a primary side ground ACGND via a switching element Q. In the secondary winding n2, the terminal 2-2 is grounded to the secondary ground ACGND, and an alternating current is induced at the terminal 2-1.

FIG. 5 is a perspective view of a main part structure showing a mounted state of a laminated transformer. The primary coil 10 has a base on which a conductor pattern corresponding to the primary winding n1 is formed.
The secondary coil 20 has a base on which a conductor pattern corresponding to the secondary winding n2 is formed. The two are separately and independently stacked. In the primary coil 10 and the secondary coil 20, spiral conductive patterns are formed on both surfaces of the insulating base, and the conductive patterns on both surfaces are connected by a communication hole provided near the center.

[0004]

However, when the primary coil and the secondary coil are separated and stacked, the magnetic coupling surface of the primary secondary winding is one of the conductor forming surfaces 1-2 & 2-1. In addition, the leakage inductance is large and the magnetic coupling of the primary and secondary windings is deteriorated. In addition, the AC resistance has a property that when there is a conductor in which current flows in the same direction at a high frequency, the effective resistance is greatly increased by a so-called proximity effect. Here, the conductor forming surface 1 which is the opposite surface of the primary and secondary windings
Since -2 & 2-1 are reversed, there is no problem, but the conductor forming surfaces 1-1 & 1-2 and the conductor forming surfaces 2-1 & 2-2 between the respective windings.
However, since the current flows in the same direction, the resistance increases. Further, regarding the stray capacitance, three pairs of the conductor forming surfaces 1-2 & 2-1, 1-1 & 1-2, and 2-1 & 2-2 become a problem. Here, since the electrostatic energy is proportional to the square of the voltage, the stray capacitance of the conductor forming surfaces 1-1 & 1-2 becomes dominant in a case where the primary voltage is about one digit higher than the secondary voltage. For example, if the transformer conversion ratio is 10:
If it is set to 1, the stray capacitance of the conductor forming surfaces 1-1 & 1-2 has a value of 100 times the stray capacitance of the conductor forming surfaces 2-1 & 2-2.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a printed coil transformer having good magnetic coupling between the primary and secondary windings and small stray capacitance existing between the coils.

[0006]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, comprises a primary coil 10 having a conductor pattern corresponding to a primary winding n1 of a transformer and a secondary winding n2 of a transformer. In the printed coil type transformer having the secondary coil 20 on which the conductive pattern to be formed is formed, the primary coil includes a right-handed spiral conductive pattern.
It is formed so that the left-handed spiral conductor pattern faces
The secondary coil is formed with a right-handed spiral conductive pattern.
It is formed so that the left-handed spiral conductor pattern faces
Of the two conductor patterns forming the primary coil.
The secondary side coil is sandwiched between the primary side
The spiral pattern of the conductor pattern of the coil and the secondary coil
A printed coil type transformer characterized by having the same orientation .

[0007]

Since the secondary coil is sandwiched by the primary coil, the magnetic coupling between the primary and secondary windings is improved. Therefore, the leakage inductance is reduced, the increase in resistance due to the proximity effect is suppressed, and the stray capacitance is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG.
FIG. 2 is a circuit diagram showing one embodiment of the present invention. In the figure,
Each conductor pattern forming surface is represented by an outer terminal i-j of the spiral pattern, i = 1 for the primary winding, i = 2 for the secondary winding, and when the terminal is on the AC ground side. j = 2, and j = 1 on the potential generation side. The two conductor forming surfaces 2-1 and 2-2 of the secondary winding are connected at the center of the spiral pattern and are adjacent to each other. The two conductor forming surfaces 1-1 and 1-2 of the primary winding are connected at the center of the spiral pattern, and are arranged at positions sandwiching the two conductor forming surfaces 2-1 and 2-2 of the secondary winding. ing.

Then, the magnetic coupling surface of the primary secondary winding has two surfaces of the conductor forming surfaces 1-1 & 2-1 and the conductor forming surfaces 1-2 & 2-2, and the leakage inductance is smaller than that of the conventional example having only one surface. Reduce to 1/4. For AC resistance,
Conductor forming surfaces 1-1 & 2-1 which are opposite surfaces of the primary and secondary windings
Current flows in opposite directions on the conductor formation surfaces 1-2 and 2-2, and the magnetic field closes between these coils, so that an increase in resistance due to the so-called proximity effect is suppressed. Further, regarding the stray capacitance, considering the case where the primary side voltage is higher than the secondary side voltage, the interval between the two conductor forming surfaces 1-1 and 1-2 of the primary winding is increased as compared with the conventional example, The stray capacitance is reduced to 1/10 to 1/2.

Next, the spiral direction of the spiral of the conductor pattern will be described. Here, the upper conductor forming surfaces 1-1 & 2-1 are left-handed, and the lower conductor forming surfaces 1-2 & 2-2 are right-handed. Here, left-handed means that, when the conductor pattern is observed from the direction of arrow G, the shape of the vortex heading from the outer terminals ij toward the center is counterclockwise (CCW). The right-handed rotation means that when the conductor pattern is observed from the direction of arrow G, the shape of the vortex heading from the outer terminals ij toward the center is clockwise (CW).

With such a configuration, the terminals 1-1 & 2
Since -1 is connected to ACGND, the potential increases in proportion to the number of turns. Therefore, the conductor forming surfaces 1-1 & 2
The AC potential increases from the outer peripheral portion toward the inner peripheral portion between −1 and the AC potential increases from the inner peripheral portion toward the outer peripheral portion between the conductor forming surfaces 1-2 and 2-2. Therefore, between the conductor forming surfaces 1-1 & 2-1 and the conductor forming surfaces 1-2 & 2-2.
Between them, the potential gradient in the radial direction becomes equal, and the stray capacitance can be reduced. Since this capacitance is a part of the stray capacitance generated on the magnetic coupling surface of the primary and secondary windings, there is an effect that the high-frequency insulation characteristics of the transformer are improved.

FIG. 2 shows an example of application to a case where there are two secondary outputs. FIG. 2A shows a case where each secondary winding is provided in parallel.
(B) shows the case of nesting. In the figure,
Each conductor pattern forming surface of the secondary winding is represented by the outer terminal 2-kl of the spiral pattern. Here, k is the output number of the secondary winding, here 1 or 2, and l
Represents the connection relationship of the terminals, where l = 2 when the terminal is on the AC ground side and l = 1 when the terminal is on the potential generation side.

In the case of FIG. 2A, the first output conductor forming surfaces 2-11 and 2-12 of the secondary winding are laminated adjacent to each other, and the second output conductor forming surface of the secondary winding is formed. 2-21 and 2-22 are stacked adjacent to each other. Then, the conductor forming surface 1 of the primary winding
-1, and 1-2, the conductor formation surface 2-11 to 2-
22 is sandwiched. In this case, due to the above-described relationship between the magnetic coupling surfaces of the primary and secondary windings, the leakage inductance is reduced, the increase in resistance due to the proximity effect is suppressed, and the stray capacitance is reduced as compared with the conventional example. effective.

In the case of FIG. 2B, the conductor forming surfaces 2-21 and 2-11 having the potential generating side terminals of the secondary winding are laminated adjacent to each other, and the AC ground side terminal of the secondary winding is connected. The conductor forming surfaces 2-12 and 2-22 are laminated adjacent to each other. Then, the conductor forming surfaces 2-21 to 2-22 of the secondary winding are sandwiched between the conductor forming surfaces 1-1 and 1-2 of the primary winding.
Accordingly, since the upper three and the lower three are divided into left-handed and right-handed, respectively, the stray capacitance can be further reduced as compared with FIG.

FIG. 3 shows an example of application to the case where a plurality of primary coils are provided. FIG. 3A shows a case where four surfaces are connected in series and the width of a conductor pattern on each surface is widened, and FIG. It shows the case of connecting in parallel. In the figure, the conductor pattern formation surface is sequentially laminated from the first layer to the eighth layer, and each conductor pattern formation surface is formed on the outer terminal i-kl of the spiral pattern.
Is represented by Here, i distinguishes the primary winding from the secondary winding, and is 1 for the primary winding and 2 for the secondary winding. k is the input number of the primary winding or the output number of the secondary winding, which is 1 or 2 here, l represents the connection relation of the terminals, and l = 2 when the terminal is on the AC ground side. , The potential generation side is represented by l = 1. In FIG. 3A, since the primary windings are connected in series, the outer terminals 1-21 and 1-12 are exceptionally internally connected.

In the case of FIG. 3A, the primary windings are connected in series in the order of the conductor forming surfaces 1-11, 1-12, 1-21 and 1-22. The current capacity is increased by halving the number of turns per conductor forming surface and doubling the width of the conductor pattern. The intermediate primary windings are formed on the conductor forming surfaces 1-12 and 1-21.
The conductor forming surface 2-2 which is one output circuit of the secondary winding
1 and 2-22 are sandwiched. Then, the intermediate primary winding is connected to the conductor forming surface 2-11 which is the other output circuit of the secondary winding.
And 2-12, and the outermost layer is covered with conductor forming surfaces 1-11 and 1-22 of the primary winding connected to the outside.

In this case, the first to fourth layers are left-handed conductor patterns, and the fifth to eighth layers are right-handed conductor patterns. The AC voltage generated in the primary winding is highest on the conductor forming surface 1-22 and lowest on the conductor forming surface 1-11.

In the case of FIG. 3B, the primary winding is composed of the first input circuit of the conductor forming surfaces 1-11 and 1-12 and the conductor forming surface 1-1.
The second input circuits -21 and 1-22 are connected in parallel. The order of lamination of the conductor forming surfaces is the same as that of FIG. 3A, but the connection states of the conductor forming surfaces of the primary windings are set in parallel. That is, the conductor formation surfaces 1-11 to 1-2 of the primary windings
An interlayer connection line connecting the two in common is provided on the center side of the spiral, and the primary windings are connected to each other because the potential of the center is common. With this configuration,
The conductor pattern for the primary winding can increase the current capacity while having the same number of turns as in FIG. 2 and the same width of the conductor pattern.

[0019]

As described above, according to the present invention,
Since the secondary coil 20 is sandwiched by the primary coil 10 and connected by an interlayer connection line provided at the center of the conductor forming surface to form the primary winding and the secondary winding of the transformer, the primary and secondary windings are formed. Due to the relationship between the magnetic coupling surfaces of the windings, there is an effect that the leakage inductance is reduced as compared with the conventional example, the increase in resistance due to the proximity effect is suppressed, and the stray capacitance is reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is an application diagram when there are two secondary outputs.

FIG. 3 is an application diagram when a plurality of primary coils are provided.

FIG. 4 is a configuration diagram of a conventional device.

FIG. 5 is a perspective view of a main part configuration showing a mounted state of the multilayer transformer.

[Explanation of symbols]

 10 Primary coil 20 Secondary coil

Claims (1)

(57) [Claims] 1. A primary coil having a conductor pattern corresponding to a primary winding of a transformer, and a secondary coil having a conductor pattern corresponding to a secondary winding of a transformer. In the printed coil type transformer, the primary side coil includes a right-handed spiral conductor pattern and a left-handed spiral pattern.
And the secondary coil includes a right-handed spiral conductor pattern and a left-handed spiral conductor pattern.
Are formed so as to face each other, and between the two conductor patterns forming the primary coil.
The primary side coil sandwiching the secondary side coil and facing the primary side coil
And the spiral orientation of the conductor pattern of the secondary coil
The printed coil type transformer is characterized in that they are the same .