JPH10135041A - Printed coil type transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make signal transfer smooth by making a primary input coil and a secondary excitation coil face each other on a ground side coil surface, and making the secondary excitation coil and a secondary output coil, respectively, face each other at a non-ground side coil surface, so as the make equal magnetic coupling for an excitation coil and an input/output coil. SOLUTION: A primary input coil 10, a secondary excitation coil 20, and a primary output coil 30 of a printed coil type transformer comprise, as a surface where a wiring pattern is formed, at least two surfaces, a ground side coil surface and a non-ground side coil surface. The order for lamination of three kinds of coils is, the input coil 10, the excitation coil 20, and the output coil 30. A front side pattern PT3-1 and a rear side pattern PT3-2 of the output coil 30, are different from each other. Lamination order such as this provides equal magnetic coupling between the input coil 10 and the output coil 30 of the excitation coil 20, resulting in symmetric property, with good linearity and frequency for the input/output characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed coil type transformer used for a circuit or the like which insulates and inputs a signal, and particularly has three coils of input, output and excitation, and outputs of common mode noise. It relates to improvements that reduce overshoot.

[0002]

2. Description of the Related Art A printed coil type transformer having two coils, input and output, is used for a switching power supply as disclosed in Japanese Patent Application Laid-Open No. 6-215951 proposed by the present applicant. When suppressing common mode noise with such a two-layer coil laminated transformer, empirically assigning the ground side coil to the opposing surface of the primary side coil and the secondary side coil, the equivalent between the primary side coil and the secondary side coil The structure was designed to reduce the effect of capacitance.

On the other hand, some signal input circuits include an excitation coil in addition to two input and output coils, and a three-coil type printed coil transformer used for such a purpose is used. I have. 9 is a cross-sectional view of such a conventional device, FIG. 10 is a wiring pattern diagram of each layer, (A) is a direct view of the primary side print coil PT1-1, and (B) is a perspective view of the primary side print coil PT1-2. (C) is a direct view of the secondary-side excitation coil PT2-1,
(D) is a perspective view of the secondary-side excitation coil PT2-2, (E).
Is a direct view of the secondary output coil PT3-1, and (F) is a perspective view of the secondary output coil PT3-2.

In FIG. 1, a primary-side input coil 10 has a pattern formed on both sides of a base plate 11.
A through hole 12 for connecting the patterns on both sides is provided. The secondary-side excitation coil 20 has patterns formed on both sides of a base plate 21 and has through holes 22 connecting the patterns on both sides. The secondary side output coil 30 has a pattern formed on both sides of a base plate 31 and a through hole 32 connecting the patterns on both sides. Here, the number of turns is the same as 6T for the primary side input coil 10, 6T for the secondary side excitation coil 20, and 6T for the secondary side excitation coil 20, but each coil is set according to the specifications of the signal input circuit. The number of turns can be individually determined for each.

The front side pattern PT of the primary side input coil 10
1-1 has a winding number of 3T, and a loop-shaped pattern is provided between the start end 13a and the relay end 13b. The back side pattern PT1-2 of the primary side input coil 10 also has a winding number of 3T, a spiral pattern is provided between the relay end 14a and the terminal end 14b, and an intermediate point 14c is provided in this spiral pattern for convenience of explanation. Have been.

The front side pattern PT of the secondary side excitation coil 20
2-1 has a winding number of 3T, is opposed to the back side pattern PT1-2, has a spiral pattern between the relay end 23a and the grounded end 23b, and has an intermediate point 23c.
Are provided in this spiral pattern for convenience of explanation. The back side pattern PT2-2 of the secondary side excitation coil 20 also has a winding number of 3T, and a spiral pattern is provided between the start end 24a and the relay end 24b. The secondary output coil 30 is
Front side pattern PT3-1 similar to secondary side excitation coil 20
In addition, a back side pattern PT3-2 is provided. still,
The front side pattern PT3-1 faces the back side pattern PT2-2.

The relay end 13b and the relay end 14a are electrically connected through the through hole 12, the relay end 23a and the relay end 24b are also electrically connected through the through hole 22, and further connected to the relay end 33a. It is also electrically connected to the relay end 34b by the through hole 32. A core 40 is provided at the center of the primary input coil 10, the secondary excitation coil 20, and the secondary output coil 30. Thus, the primary side input coil 10 and the secondary side excitation coil 2
0 indicates that the pattern surfaces having grounded terminations are opposed to each other according to a rule of thumb. However, the secondary output coil 3
For 0, only the ungrounded surface of the primary input coil 10 or the ungrounded surface of the secondary excitation coil 20 remains, so that one of these ungrounded surfaces and the ground surface of the secondary output coil 30 are opposed to each other. I was This is because the identity of the stacked state of the secondary excitation coil 20 and the secondary output coil 30 is considered.

FIG. 11 is a circuit diagram of a signal input circuit having three types of windings of input, output and excitation. In the figure, a primary side input coil 10 includes a primary winding N ₁ , a secondary side excitation coil 20
Is the auxiliary winding Naux, and the secondary output coil 30 is the secondary winding N ₂
Has been used as Signal input to the primary winding N ₁ is, for example, a voltage signal from the current transformer, since this input signal to obtain an output signal of a wide frequency band from a DC component to an AC component, for excitation from auxiliary winding Naux Is supplied.

[0009] Input signal Vin, the resistance R ₁ and capacitor C ₁
And a pair of reverse-connected diodes D ₁ and D ₂ for preventing the excitation signal from leaking to the input signal side.
It is applied to the primary winding N _1. On the other hand, a pulse signal having a predetermined frequency from the excitation source, through the CR circuit of the resistor R ₃ and capacitor C _4, is applied to the auxiliary winding Naux. This excitation signal acts as a modulation signal for transmitting the DC component of the input signal using a transformer. The signal induced in the secondary winding N ₂ is transmitted via a pair of reverse-connected diodes D ₃ and D ₄ which prevent the excitation signal from leaking to the output signal side.
Smoothed by the capacitor C _2, the output signal is further sent through the CR circuit of the resistor R ₂ and capacitor C _3. here,
Turns ratio of the primary winding N ₁ and the secondary winding N ₂ is 1: 1,
The output signal has the same voltage as the input signal.

[0010]

FIG. 12 is an explanatory diagram in the case where common mode noise is connected to the signal input circuit of FIG. For example, in an application for detecting a load current of an inverter circuit that drives an electric motor, a switching current of the inverter circuit largely overlaps with an output signal as common mode noise. Then, in an application in which the output signal is a load current signal, it is difficult to accurately measure the load current, and in extreme cases, the output signal may overshoot, and the operation of the signal input circuit may be reduced. There was a problem of causing serious trouble. An object of the present invention is to provide a laminated transformer having three types of coils of input, output, and excitation, and to provide a printed coil type transformer having a structure for reducing common mode noise. I do.

[0011]

In order to achieve the above object, the present invention provides a primary input coil 10 to which an input signal is applied.
A secondary output coil 30 that outputs an output signal corresponding to the input signal applied to the primary input coil; and a secondary output coil 30 that supplies an excitation signal having a predetermined period to the primary input coil and the secondary output coil. In the printed coil type transformer having the secondary side excitation coil 20, the primary side input coil, the secondary side excitation coil, and the secondary side output coil have a ground side coil surface and a non-ground side as a surface on which a wiring pattern is formed. It has at least two coil surfaces, and the order of lamination of the three types of coils is a primary input coil, a secondary excitation coil, and a secondary output coil, in which the primary input coil and the secondary The excitation coils oppose each other on the ground side coil surface, and the secondary side excitation coil and the secondary side output coil oppose each other on the non-ground side coil surface.

According to the configuration of the present invention, the three types of coils are stacked in the order of the primary input coil, the secondary excitation coil, and the secondary output coil, so that the primary input coil has the primary input coil. Since the magnetic coupling between the coil and the secondary side output coil becomes equal and symmetry is obtained, the linearity of input and output and the frequency characteristic are improved. Further, the distance between the primary side input coil and the secondary side output coil is increased, the capacitance between the coils is reduced, and noise is hardly transmitted. In particular, if the primary side input coil and the secondary side excitation coil face each other on the ground side coil surface, and the secondary side excitation coil and the secondary side output coil face each other on the non-ground side coil surface, the Is minimized, and output overshoot caused by common mode noise can be suppressed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a wiring pattern diagram of each layer showing an embodiment of the present invention. In FIG. 1, components having the same functions as those in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted. The cross-sectional view in this embodiment is the same as FIG. Here, the stacking order of the three types of coils is the primary side input coil 10,
In order secondary excitation coil 20 and the secondary side output coil 30 is similar to FIG. 10, but the front side pattern of the secondary side output coil 30 PT3-1 ^* and backside pattern PT3-2 ^* are different. That is, the front-side pattern PT3-1 ^* is opposed to the back-side pattern PT2-2, and has a spiral pattern having 3T turns between the start end 33a ^* and the relay end 33b ^* . The back side pattern PT3-2 ^* has a spiral pattern with 3T turns between the relay end 34a ^* and the grounded end 34b ^* .

Next, a theoretical analysis of the device configured as described above is performed. 2A and 2B are explanatory diagrams of noise transmitted between the coils. FIG. 2A is a model diagram, and FIG. 2B is a potential diagram viewed from a side. Here, the front side pattern formed on the coil 1 is the hot side, that is, the surface on which the signal voltage application / generation side terminals exist, and the back side pattern formed on the coil 2 is the cold side, that is, the ground side terminal. It is an existing surface. A core hole 4 for passing the core 40 is provided in the front side pattern and the back side pattern.
2 are provided, and coincide with the center axis Z of each of the coils 1 and 2. The distance from the coil center to the innermost circumference is r ₁ , and the distance from the coil center to the outermost circumference is r ₂ . The distance between the coils 1 and 2 is d. At this time, the equivalent capacitance Ceq is given by the following equation.

(Equation 1)

Here, ε is the dielectric constant between the coils 1 and 2, r
Is the coil radius, v ₁ (r) is the potential distribution of the coil 1 in the radius r direction, and v ₂ (r) is the potential distribution of the coil 2 in the radius r direction. v is a voltage per turn of the coil 1, for example, assuming that the number of turns of the primary winding is Np and the applied voltage is Ein.
v = Ein / Np. n is the number of turns of an arbitrary coil, for example, the number of turns of the primary winding corresponds to Np. At this time, the impedance Z between the coils satisfies the following relationship. Z = (ωCeq) ⁻¹ (2) That is, the larger the equivalent capacitance Ceq, the lower the impedance Z, and the more easily noise is transmitted.

Now, it is assumed that the number of turns of the coil 1 is n ₁ .
Then, the potential distribution v ₁₁ (r) in the radius r direction of the hot side pattern of the coil 1 and the potential distribution v ₁₂ (r) in the radius r direction of the cold side pattern are represented by the following equations.

(Equation 2) Here, n ₁ v is a voltage applied / generated to the hot side terminal of the coil 1. As for the coil 2, if the number of turns is n ₂ , the potential distribution v ₂₁ (r) in the radius r direction of the hot side pattern of the coil 2 and the potential distribution v ₂₂ (r) in the radius r direction of the cold side pattern are the same. It is represented by the following equation.

FIGS. 3A and 3B are explanatory diagrams of noise transmitted between two kinds of adjacent coils. FIG. 3A is a schematic diagram showing a cross section of the coil, FIG. 3B is a schematic diagram showing a wiring state of the coil, and FIG. The figure, (D), the potential difference ΔV between the coils n ₁₂ and n ₂₁ , (E)
Indicates the square of the potential difference ΔV ² , and (F) indicates the equivalent capacitance. The wiring patterns formed on both sides of the base plate 11
A coil n ₁₁ and the coil n _12, the wiring patterns formed on both surfaces of the base plate 21 is a coil n ₂₁ and the coil n _22. Here, the hot side of each coil is represented by H, and the cold side is represented by C. Here, “*” is used to indicate the high potential side, but since the positive potential is considered, the hot side H is the high potential side.

The coil n _12, a potential difference ΔV between the n ₂₁ is zero V becomes the center O, the peripheral portion r _O in the hot-side terminal voltage applied n
and the voltage distribution in the direction of the radius r changes linearly. Here, the number of turns of each of the coils n ₁ and n ₂ is the same. To simplify the calculations, the distance r ₁ to the innermost circumference is set to zero from the center of O, the distance r ₂ to the outermost periphery and r _O. Then, the equivalent capacitance Ceq satisfies the following relationship. Ceq = (π / 2) x (ε / d) xr _O ² (5)

FIGS. 4A and 4B are explanatory diagrams of equivalent capacitance on a disk-shaped in-plane equipotential surface, wherein FIG. 4A is a model diagram and FIG. 4B is an explanatory diagram of equivalent capacitance. When the reference equivalent capacitance Ceq ref is obtained between the single potential plane nv and the zero plane, the following relationship is satisfied. Ceq ref = πx (ε / d) × r _O ² (6) That is, assuming that Ceq ref is a reference equivalent capacity, the equivalent capacity of the equation (5) is a value of 1/2.

FIG. 5 is an explanatory view showing the case of one type of coil.
(A) shows the difference between hot / cold, (B) shows the difference in offset voltage, and (C) shows the difference in the start of winding. 1
There are 2 ³ = 8 patterns depending on which of the two surfaces of the seed coil is selected to be the hot side, which is the high potential side, and which surface is to be wound.

FIG. 6 is a diagram for explaining a combination of three types of coils without distinction between the primary side and the secondary side. FIG.
(B) is a figure for calculating the equivalent capacitance.
The coils n ₁₁ , n ₁₂ , n ₂₁ ,
There are n ₂₂ , n ₃₁ and n _32, which side of hot / cold in each coil is indicated by H and C, and which side of the high potential side is indicated by *. .

In the figure for calculating the equivalent capacitance, the
The outer peripheral potential uses 1, 0 for each surface with reference to the potential nv.
Is displayed. And the potential difference between adjacent surfaces
, Three columns, upper, middle, and lower, are provided.
The upper column shows the potential at the center of the coil, higher than the surroundings.
A indicates the case where it is not, and V indicates the case where it is low. Middle column is coil
n₁₂, N_{twenty one}Is the state of the potential difference between the outermost coils of the coil
It is displayed in a range of +2 to -2 with respect to the potential nv.
It is displayed as an enclosed integer. The lower column is coil n₁₂, N _{twenty one}Electricity between
Displays the state of the position difference at the center of the coil.
It is displayed as an integer in the range of +1 to -1 based on the position nv.
You. Then, the equivalent capacitance Ceq between the adjacent surfaces is Ceq
 It is displayed based on ref. Coil n_{twenty two}, N₃₁while
The same applies to the potential difference. The Ceq coefficient is expressed as coil n
₁₂, N_{twenty one}The equivalent capacitance Ceq between the coil n_{twenty two}, N₃₁Etc.
This is the sum of the valency capacity Ceq.

FIG. 7 is an explanatory diagram of an embodiment in which the equivalent capacitance coefficient is the minimum among the combinations of the three types of coils, and there are four types (A) to (D). In (A), the ground side coil C is opposed between the coils n ₁₂ and n ₂₁ , and the non-ground side coil H on the high potential side is opposed between the coils n ₂₂ and n ₃₁ .
In (B), the non-ground side coil H faces between the coils n ₁₂ and n ₂₁ , and the ground side coil C on the high potential side faces between the coils n ₂₂ and n ₃₁ . As for (C), the ground-side coil C on the high potential side faces each other between the coils n ₁₂ and n ₂₁ , and the non-ground side coil H faces between the coils n ₂₂ and n ₃₁ . As for (D), the non-ground side coil H on the high potential side faces each other between the coils n ₁₂ and n ₂₁ , and the ground side coil C faces between the coils n ₂₂ and n ₃₁ . When the above is categorized, the ground-side coils C or the non-ground-side coils H face each other,
When the surfaces having the same offset potential face each other, the potential difference is minimized, and the equivalent capacitance coefficient is minimized.

FIG. 8 is an explanatory view of a comparative example of a combination of three types of coils, and illustrates five typical cases (A) to (E). If the points explained in the case of the type 1 coil are simply applied to the type 3 coil, there are 8 ³ = 512 cases. However, when considering a meaningful combination,
Since the offset potentials of the second and third coils are determined at the beginning of the winding of the coils, the cases of the offset potentials are reduced, and in those cases, there are 2 ² = 4 cases. In addition, since the start of winding is a concept having a meaning when the second and third coils are on the same side or different sides, or on the same side or a different side as the first coil, the winding start of the first coil is started. Cases are excluded and 2 ² = 4. As a result, there are 4 ³ = 64 meaningful combinations.

In (A), in the first to third coils,
The upper surface is the non-ground side coil H on the high potential side, the lower surface is the ground side coil C, and the equivalent capacitance coefficient is 1.00. (B)
In the first to third coils, the upper surface is the ground-side coil C on the high potential side, the lower surface is the non-ground side coil H, and the equivalent capacitance coefficient is 1.00. Regarding (C), first to first
In the third coil, the upper surface is a non-grounded coil H, the lower surface is a grounded coil C on the high potential side, and the equivalent capacitance coefficient is 1.00.
It has become. Regarding (D), in the first to third coils, the upper surface is the ground coil C, the lower surface is the non-ground coil H on the high potential side, and the equivalent capacitance coefficient is 1.00.

FIG. 5E is an explanatory diagram of an embodiment in which the equivalent capacitance coefficient among the combinations of the three types of coils is maximized. Between the coils n ₁₂ and n ₂₁ , the non-ground side coil H on the high potential side and the ground side coil C face each other, and between the coils n ₂₂ and n ₃₁ , the non-ground side coil H faces each other. Is on the low potential side, and the other is on the high potential side. At this time, the equivalent capacitance coefficient is 3.83, which is the maximum value among the above 64 combinations, that is, the worst state.

In the above-described embodiment, a single coil is formed of two layers. However, the present invention is not limited to this, and the number of stacked single coils is three or more. The same applies.

[0028]

As described above, according to the present invention, 3
Since the order of lamination of the seed coils is the order of the primary side input coil, the secondary side excitation coil, and the secondary side output coil, the magnetic coupling between the excitation coil, the input coil and the output coil is equal, and symmetry is obtained. Therefore, there is an effect that the signal transmission of the input / output signal is performed harmoniously. Further, since the distance between the primary side input coil and the secondary side output coil is separated by the amount of the excitation coil, there is an effect that the capacitance between the coils is reduced and noise is hardly transmitted. Furthermore, it is necessary to insert an insulating layer between the primary side input coil and the secondary side output coil, but when inserting the primary side input coil between the secondary side excitation coil and the secondary side output coil, Requires two insulating layers, whereas this embodiment requires only one insulating layer. When the number of insulating layers is small, there is an effect that the transformer can be thin and the manufacturing cost is reduced.

Further, the primary side input coil and the secondary side excitation coil face each other on the ground side coil surface, and the secondary side excitation coil and the secondary side output coil face each other on the non-ground side coil surface. Therefore, there is an effect that the equivalent capacitance is reduced and output overshoot caused by common mode noise is suppressed.

[Brief description of the drawings]

FIG. 1 is a wiring pattern diagram of each layer showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of noise transmitted between coils.

FIG. 3 is an explanatory diagram of noise transmitted between adjacent two kinds of coils.

FIG. 4 is an explanatory diagram of an equivalent capacitance of a disk-shaped in-plane equipotential surface.

FIG. 5 is an explanatory diagram of the case of class 1 coil.

FIG. 6 is a diagram illustrating a combination of three types of coils without distinction between a primary side and a secondary side.

FIG. 7 is an explanatory diagram of an embodiment in which an equivalent capacitance coefficient is minimized among combinations of three types of coils.

FIG. 8 is an explanatory diagram of a comparative example of a combination of three types of coils.

FIG. 9 is a cross-sectional view of a conventional three-coil laminated transformer.

FIG. 10 is a wiring pattern diagram of each layer.

FIG. 11 is a circuit diagram of a signal input circuit having three types of windings: input, output, and excitation.

FIG. 12 is a diagram illustrating a case where a common mode noise source is connected to the signal input circuit of FIG. 11;

[Explanation of symbols]

 Reference Signs List 10 Primary side input coil 20 Secondary side excitation coil 30 Secondary side output coil 40 Core 50 Common mode noise source

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shuichi Matsuda 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation

Claims (2)

[Claims] A primary input coil to which an input signal is applied, and a secondary output coil for outputting an output signal corresponding to the input signal applied to the primary input coil.
0) and a secondary excitation coil (2) for supplying an excitation signal of a predetermined period to the primary input coil and the secondary output coil.
0), wherein the primary-side input coil, the secondary-side excitation coil, and the secondary-side output coil have a ground-side coil surface and a non-ground-side coil surface as a surface on which a wiring pattern is formed. The order of lamination of the three types of coils is a primary input coil, a secondary excitation coil, and a secondary output coil, and the primary input coil and the secondary excitation coil are A printed coil type transformer, wherein each of the transformers opposes on a ground side coil surface, and the secondary side excitation coil and the secondary side output coil oppose each other on a non-ground side coil surface. 2. A primary input coil (10) to which an input signal is applied, and a secondary output coil (3) for outputting an output signal corresponding to the input signal applied to the primary input coil.
0) and a secondary excitation coil (2) for supplying an excitation signal of a predetermined period to the primary input coil and the secondary output coil.
0), wherein the primary-side input coil, the secondary-side excitation coil, and the secondary-side output coil have a ground-side coil surface and a non-ground-side coil surface as a surface on which a wiring pattern is formed. The order of lamination of the three types of coils is a primary input coil, a secondary excitation coil, and a secondary output coil, and the primary input coil and the secondary excitation coil are A printed coil type transformer characterized in that the coil faces each other on a non-ground side coil surface, and the secondary side excitation coil and the secondary side output coil face each other on a ground side coil surface.