JPH04302111A - High freqyebcy transformer - Google Patents

Abstract

PURPOSE:To obtain a high frequency transformer having low copper loss even when it is brought into a high frequency state and a winding can be formed easily. CONSTITUTION:The title transformer consists of a primary side copper foil winding 1, composed of a recessed type copper foil electrode and a 180 deg.-rotated inversed recess type copper foil electrode which is constituted in such a manner that a surface-insulated copper foil winding is turned back in bellow form, a secondary-side copper foil winding 2, which is composed of a recess type copper electrode and a 180 deg.-rotated inversed type copper foil electrode constituted in such a manner that a surface-insulated copper foil winding is turned back in bellow-like form and interlocked alternately with the primary-side copper foil winding 1, and a core which is inserted into the recess and the inverted recess of the copper foil electrode.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency transformer that handles high frequency signals of several MHz, and more particularly to improvements in the windings of high frequency transformers.

0002

2. Description of the Related Art When a sinusoidal AC voltage Vp of frequency f is applied to the primary side of a transformer, the magnetic flux density B induced in the core can be expressed by the following equation.

B=Vp/(2πfn1·Seff)...■Here, n1 is the number of turns of the primary winding, and Seff is the effective cross-sectional area of the core. Therefore, as the frequency f increases, the magnetic flux density within the core decreases, making it possible to downsize the core.

0004

However, due to the following skin effect and proximity effect, the current distribution flowing through the winding becomes biased, leading to a substantial increase in equivalent resistance, that is, an increase in copper loss as the frequency increases. (2) Skin Effect FIG. 11 is an explanatory diagram of the skin effect. FIG. 11(A) shows a cross section of a conductor, and FIG. 11(B) shows the current density in the diametrical direction of the conductor. The skin effect is a phenomenon in which current flows more concentrated on the surface of a conductor as the frequency increases, and is caused by leakage magnetic flux around the conductor penetrating into the inside of the conductor. The skin thickness δ is given by the following formula using the skin effect constant K.

[0005] δ=K/f 1/2 [mm]...■Here, f is the frequency. If f is 1MHz and the material of the conductor is copper, K is 66.1, so δ is 66.1μ
m. Therefore, in the case of a single wire, the alternating current resistance can be reduced by making the wire diameter as thick as the skin.

However, since there is a certain limit to the current density that can be passed through the copper wire, there is a problem that the load current on the secondary side is limited and the space factor decreases due to the subdivision of the winding. ■ Proximity Effect Figure 12 is an explanatory diagram of the proximity effect. Figure 12 (A) shows the case where currents flow in the same direction, and Figure 12 (B) shows the case where currents flow in opposite directions. ing.

[0007] Proximity effect is when there is a conductor through which current flows in close proximity, the magnetic field created by this conductor is not uniform across the cross section of the conductor, so the magnetic field inside the conductor is not completely canceled out and losses increase. Say something. When flowing in the same direction, the current is distributed on the outside, and when flowing in the opposite direction, the current is distributed on the inside. To alleviate this problem, adjacent conductors may be spaced apart by approximately the thickness of the skin. However, if this is done, there is a problem that the shape of the transformer becomes larger.

In FIG. 13, the conductor is made of copper foil, and these two copper foils are arranged in parallel with a distance d between them. Figure 1
4 is a characteristic diagram illustrating AC resistance Rac in the arrangement of FIG. 13. The vertical axis shows the AC resistance Rac based on the DC resistance Rdc, and the horizontal axis shows the distance d. The dimensions w of the copper foil are 5 mm, the thickness t is 100 μm, and the frequency f
This is an example of calculation when the frequency is 1 MHz. R for copper foil alone
ac/Rdc is 1.5, but increases to 2.2 in the same direction (e.g., inductors with coiled windings), and increases to 2.2 in the opposite direction, e.g., with alternating primary and secondary windings. (transformer), it decreased to 1.3.

For the reasons mentioned above, as the frequency increases, copper loss increases due to the skin effect and proximity effect, leading to an increase in the temperature of the transformer, which causes breakdown of magnetic permeability and deterioration of the winding insulation. It had become.

The applicant has also filed a proposal for solving the above-mentioned problems in Japanese Patent Application No. 186563/1999. However, this proposal also did not mention insulation between the primary and secondary windings.

[0011] In addition, when manufacturing a tightly coupled copper foil winding as described above, when soldering the foils together or soldering for electrode attachment, dielectric breakdown due to unevenness at the solder joints and soldering may occur. The insulation deteriorates due to the work, and the occupancy rate deteriorates due to the bending of the winding due to the steel of the soldered part, and this type of phenomenon is particularly noticeable in the electrode part.

The present invention has been made in view of these points, and its object is to provide a high-frequency transformer that has low copper loss even at high frequencies and whose windings are easy to manufacture.

[0013]

[Means for Solving the Problems] The first means for solving the above problems is to provide a copper foil winding whose surface is insulated, which is a combination of a concave copper foil electrode and a reversely concave copper foil electrode rotated by 180 degrees. The primary side copper foil winding is constructed by folding back into a bellows shape, the copper foil winding is made up of a combination of a concave copper foil electrode and a reverse concave copper foil electrode rotated 180 degrees, and the copper foil winding is insulated on the surface. It is characterized by comprising: secondary copper foil windings that are folded back and interlocked with the primary copper foil windings, and a core that is inserted into the recesses of the concave and reversely concave copper foil electrodes. It is something to do.

A second means for solving the above problem is to fold a copper foil winding, which is made of a combination of a concave copper foil electrode and a reverse concave copper foil electrode rotated by 180 degrees and whose surface is insulated, into a bellows shape. It consists of a combination of a primary copper foil winding, a concave copper foil electrode, and a reverse concave copper foil electrode rotated 180 degrees, and the copper foil winding whose surface is insulated is folded back into a bellows shape. It consists of a combination of a secondary copper foil winding and a concave copper foil electrode whose surface is insulated, and a shield foil folded back into a bellows shape.The primary copper foil winding, the shield foil, and the secondary copper foil It is characterized by having windings that are interlocked with each other alternately, and a core inserted into a recess in concave and reversely concave copper foil electrodes and a shield foil.

[0015]

[Operation] In the present invention, the copper foil winding, which is made up of a combination of a concave copper foil electrode and a reversely concave copper foil electrode rotated by 180 degrees, and whose surface is insulated is folded back into a bellows shape, is used. Since the copper foil windings and the secondary copper foil windings are arranged to mesh alternately, the direction of the current flowing through each winding is opposite, reducing the influence of proximity effect and reducing copper loss. decreases. In addition, manufacturing of the winding becomes extremely simple.

Furthermore, the shielding foil reduces line capacitance and improves high frequency insulation between the primary and secondary sides.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a structural diagram showing a developed state of a copper foil winding used in an embodiment of the present invention. Note that the foil may be constructed using a metal other than copper, but copper is suitable in terms of resistivity.

In this embodiment, the winding is made of copper foil, and one concave copper foil is one turn (n-1 pieces of copper foil for n turns). FIG. 1(a) shows five basic two-turn copper foil windings (alternate combination of two concave electrodes and one reverse concave electrode) connected together. That is, by folding the copper foil winding shown in FIG. 1(a) into a bellows shape as shown in FIG. 2, five sets of two-turn windings are connected. Then, the ends of the electrodes of each two turns of the winding are connected to each other. In this case, A, D, E, H, I
are electrically connected, and B, C, F, G, and J are electrically connected. In this case, the winding directions are opposite to each other every two turns, but the direction of the current is also opposite every two turns, and the generated magnetic fields are in the same direction.

FIG. 1(b) shows three sets of basic three-turn copper foil windings (alternate combination of three concave electrodes and two reverse concave electrodes) connected together. . That is, by folding the copper foil winding shown in FIG. 1(b) into a bellows shape as shown in FIG. 2, three sets of three turns of winding wire are connected. Then, the ends of the electrodes of each three-turn winding are connected to each other. In this case, a, d, and e are electrically connected, and b, c, and f are electrically connected. When this winding is used on the secondary side, the winding directions are opposite to each other for every 3 turns, but by connecting the ends in opposite directions, it is possible to configure a transformer. On the secondary side, the currents of the windings every three turns are added.

FIG. 3 shows the primary winding and secondary winding.
Bite each other alternately as shown. In this case, as shown in Figure 1, by making the number of copper foils on the primary winding equal to the number of copper foils on the secondary winding (15 each for the concave type and the reverse concave type in Figure 1), It is expected that the magnetic fields generated by both will be uniform and the AC resistance will be the smallest. However, as the number of laminated layers increases, the thickness of the entire winding becomes thicker, which becomes a trade-off with the current flowing. in fact,
A current density j of 2 to 3 A/mm2 is suitable.

[0022] When actually manufacturing, prepare a copper foil approximately as thick as the skin, and cut it as shown in Figure 1. After that, insulation is applied to the surface of the copper foil. Insulation is done by pasting insulating tape or applying an insulating material. and,
The copper foil winding is folded back into a bellows shape as shown in FIG. This is done on both the primary and secondary sides to make them engage as shown in FIG. In this case, a transformer winding can be constructed in which two windings are stacked one on top of the other. In addition, as shown in FIGS. 3A and 3B, better engagement can be achieved by providing folding margins in the portions that sandwich the mating windings.

FIG. 4 shows a case where the winding on one side (the primary winding in this figure) has one turn. In this case, the concave copper foil is used as is for one turn of the winding, and only the multiple turns of the winding are made into a bellows shape. In this case, the primary and secondary windings are completely alternately arranged.

[0024] As described above, when the winding is made of copper foil, the line capacitance between the primary and secondary becomes larger than usual. This allows AC signals to pass through, which is equivalent to a reduction in insulation, especially in the high frequency range.

Therefore, as a second embodiment, a shield material consisting of a combination of concave electrodes as shown in FIG. so that it is sandwiched between. In addition, this shielding material 3 is
It is made of copper foil, and the surface is insulated.

Then, a terminal (shield terminal 9) is provided on the shield material 3, and the terminal is connected to the earth terminal (shield terminal 9) of the primary winding.
A reliable shielding effect can be obtained by connecting it to either one of the primary winding terminals 5 and 6). By providing the shield material 3 in this way, the insulation between the primary and secondary is further improved.

FIG. 7 is a front view of the high frequency transformer constructed in this way, FIG. 8 is a side view, FIG. 9 is a top view, and FIG. 10 is a perspective view. As shown in FIG. 10, each terminal (primary winding terminals 5, 6, secondary winding terminals 7, 8, shield terminal 9) is held together by bolts and nuts, and the wiring is connected. Further, the core used is of EE or EI type.

As explained above, even when manufacturing closely coupled copper foil windings, since each winding is constructed from a single piece of copper foil, problems due to soldering do not occur. Further, it is sufficient to manufacture the primary winding and the secondary winding separately and combine them, making it possible to manufacture a tightly coupled transformer winding extremely easily.

[0029]

As described in detail above, according to the invention as set forth in claim 1, it is possible to realize a high frequency transformer which has low copper loss even when the frequency is increased and whose winding is easy to manufacture. Further, according to the second aspect of the invention, it is possible to realize a high frequency transformer that has excellent insulation properties between the primary and secondary windings at high frequencies and is easy to manufacture.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the configuration of a winding used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a folded state of the winding shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a folded state of the winding shown in FIG. 1;

FIG. 4 is an explanatory diagram showing the arrangement of windings.

FIG. 5 is a configuration diagram showing a planar configuration of a shield winding used in a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a winding configuration of a second embodiment of the present invention.

FIG. 7 is a front view showing the front of a transformer manufactured according to the present invention.

FIG. 8 is a side view showing the side surface of a transformer manufactured according to the present invention.

FIG. 9 is a top view showing the top surface of a transformer manufactured according to the present invention.

FIG. 10 is a perspective view showing a perspective view of a transformer manufactured according to the present invention.

FIG. 11 is an explanatory diagram for explaining the skin effect.

FIG. 12 is an explanatory diagram for explaining the proximity effect.

FIG. 13 is an explanatory diagram showing the arrangement of copper foil windings.

FIG. 14 is an explanatory diagram illustrating AC resistance of parallel windings.

[Explanation of symbols]

1 Primary winding 2 Secondary winding 3 Shield material 4 Core

Claims (2)

[Claims] Claim 1: A primary copper foil winding constructed by folding a copper foil winding whose surface is insulated into a bellows shape, which is a combination of a concave copper foil electrode and a reversely concave copper foil electrode rotated by 180 degrees. It consists of a combination of a concave copper foil electrode and a reversely concave copper foil electrode rotated 180 degrees, and the copper foil winding, whose surface is insulated, is folded back into a bellows shape, and the copper foil winding is arranged alternately with the primary copper foil winding. A high frequency transformer comprising interlocked secondary copper foil windings and a core inserted into a recess of a concave and reversely concave copper foil electrode. 2. A primary copper foil winding constructed by folding a copper foil winding whose surface is insulated into a bellows shape, which is a combination of a concave copper foil electrode and a reversely concave copper foil electrode rotated by 180 degrees. and a secondary side copper foil winding formed by folding a copper foil winding whose surface is insulated into a bellows shape, which is a combination of a concave copper foil electrode and a reverse concave copper foil electrode rotated by 180 degrees; It consists of a combination of concave copper foil electrodes whose surfaces are insulated, folded back into a bellows shape, and equipped with a shield foil.
It is composed of a primary copper foil winding, a shield foil, and a secondary copper foil winding that are interlocked with each other alternately, and the core is inserted into the recess of the concave and reverse concave copper foil electrodes and the shield foil. High frequency transformer.