JP4400557B2 - Noise suppression circuit - Google Patents

Description

  The present invention relates to a noise suppression circuit that suppresses noise propagating on a conductive wire.

  Power electronics devices such as switching power supplies, inverters, lighting circuits for lighting devices, and the like have a power conversion circuit that converts power. The power conversion circuit has a switching circuit that converts direct current into rectangular alternating current. For this reason, the power conversion circuit generates a ripple voltage having a frequency equal to the switching frequency of the switching circuit and noise associated with the switching operation of the switching circuit. This ripple voltage and noise adversely affect other devices. Therefore, it is necessary to provide a means for reducing ripple voltage and noise between the power conversion circuit and another device or line.

  Recently, power line communication has been considered promising as a communication technique used in building a communication network in the home, and its development is being promoted. In power line communication, communication is performed by superimposing a high-frequency signal on the power line. In this power line communication, noise is generated on the power line due to the operation of various electric / electronic devices connected to the power line, which causes a decrease in communication quality such as an increase in error rate. Therefore, a means for reducing noise on the power line is required. In power line communication, it is necessary to prevent a communication signal on the indoor power line from leaking to the outdoor power line.

  In order to suppress these noises, it is effective to provide a line filter in a power supply line, a signal line, or the like. As the line filter, a filter including an inductance element (inductor) and a capacitor, a so-called LC filter is often used. The LC filter includes a T-type filter and a π-type filter in addition to one having one inductance element and one capacitor. A general noise filter for electromagnetic interference (EMI) countermeasures is also a kind of LC filter. A general EMI filter is configured by combining discrete elements such as a common mode choke coil, a normal mode choke coil, an X capacitor, and a Y capacitor.

  Noise that propagates through two conductive lines includes normal mode (differential mode) noise that causes a potential difference between the two conductive lines, and common mode noise that propagates through the two conductive lines in the same phase. There is.

  Patent Document 1 describes a line filter using a transformer. This line filter includes a transformer and a filter circuit. The secondary winding of the transformer is inserted into one of the two conductive wires that transport power supplied from the AC power source to the load. Two input ends of the filter circuit are connected to both ends of the AC power source, and two output ends of the filter circuit are connected to both ends of the primary winding of the transformer. In this line filter, a noise component is extracted from a power supply voltage by a filter circuit, and this noise component is supplied to the primary winding of the transformer, whereby the power supply voltage is applied on the conductive line in which the secondary winding of the transformer is inserted. The noise component is subtracted from. This line filter reduces noise in the normal mode.

  Patent Document 2 describes a low-pass filter composed of three impedance elements. This low-pass filter has two high impedance elements inserted in series on one of two conductive lines, one end connected between the two high impedance elements, and the other end of the two conductive lines. And a low impedance element connected to the other of the two. Each of the two high impedance elements is configured by a parallel connection circuit of a coil and a resistor, and the low impedance element is configured by a capacitor. This low-pass filter reduces normal mode noise.

Patent Document 3 describes a normal mode noise filter circuit for reducing normal mode noise and a common mode noise filter circuit for reducing common mode noise. The normal mode noise filter circuit is composed of two coils inserted in two conductive wires and a capacitor connecting the middle windings of the coils. The common mode noise filter circuit is composed of two coils inserted into two conductive wires, and two capacitors provided between the windings of each coil and the ground.
JP-A-9-102723 Japanese Patent Laid-Open No. 5-121988 (FIG. 1) Japanese Patent No. 2784833 (FIG. 6)

  Since the conventional LC filter has a specific resonance frequency determined by inductance and capacitance, there is a problem that a desired attenuation can be obtained only in a narrow frequency range. The filters described in Patent Documents 2 and 3 also have the same problems as conventional LC filters because the principle of noise reduction is the same as that of conventional LC filters.

  Further, in the line filter described in Patent Document 1, theoretically, the noise component can be completely removed if the coupling coefficient of the transformer is 1 and the filter circuit does not affect the line filter. it can. However, in practice, it is impossible to set the coupling coefficient of the transformer to 1, and as the coupling coefficient decreases, the attenuation characteristic deteriorates. In particular, when a filter circuit is constituted by a capacitor, a series resonance circuit is constituted by the capacitor and the primary winding of the transformer. Therefore, the impedance of the signal path including the capacitor and the primary winding of the transformer is reduced only in a narrow frequency range near the resonance frequency of the series resonance circuit. As a result, this line filter can remove noise components only in a narrow frequency range. For these reasons, the actually configured line filter has a problem that noise components cannot be effectively removed in a wide frequency range.

  By the way, in each country, various regulations are often provided for noise emitted from an electronic device to the outside via an AC power supply line, that is, a noise terminal voltage. For example, in the standard of CISPR (International Radio Interference Special Committee), the standard of the noise terminal voltage is set in the frequency range of 150 kHz to 30 MHz. When noise is reduced in such a wide frequency range, the following problems occur particularly with respect to noise reduction in a low frequency range of 1 MHz or less. That is, in the low frequency range of 1 MHz or less, the absolute value of the impedance of the inductance element is represented by 2πfL, where L is the inductance of the inductance element and f is the frequency. Therefore, in general, in order to reduce noise in a low frequency range of 1 MHz or less, a filter including an inductance element having a large inductance is required. As a result, the shape of the inductance element (core and winding) increases, and the filter as a whole also increases in size.

  Furthermore, in the case of a filter having a plurality of inductance components, if each inductance component is configured to be independent and separated, for example, the characteristic value of each inductance component is likely to vary due to a lot difference in the actual manufacturing stage. There is also a possibility that the noise suppression effect may vary. In addition, the characteristic value may vary depending on the difference in component arrangement.

  The present invention has been made in view of such problems, and its object is to suppress noise over a wide frequency range without increasing the size and to suppress variation in the characteristics of inductance components and to improve noise. An object of the present invention is to provide a noise suppression circuit capable of obtaining a suppression effect.

A noise suppression circuit according to a first aspect of the present invention is a circuit that suppresses normal mode noise that is transmitted through first and second conductive lines and causes a potential difference between these conductive lines. Including first and second windings inserted in series with each other, a third winding and a capacitor connected in series, one end of the first winding and the second winding. The other end is connected to the second conductive line, and the first and second windings, and the common core around which the third winding is wound It is.

In the noise suppression circuit according to the first aspect of the present invention, the first and second windings, the third winding, and the common core around which the first and second windings are wound , and the first and second windings in each winding portion. Two inductors as well as a third inductor are formed. Since each inductor is formed of the same common core, it is magnetically coupled to each other.
Here, when the normal mode voltage Vi is applied to the first winding side between the first and second conductive lines, the voltage Vi is mainly applied to the third inductor in the series circuit with the first inductor. And a predetermined voltage in the same direction is generated between both ends of the first inductor and both ends of the series circuit. Since the first inductor and the second inductor are formed of the same common core and are magnetically coupled to each other, both ends of the second inductor are generated according to a predetermined voltage generated between both ends of the first inductor. A predetermined voltage is also generated between them. Since one end of the series circuit is connected between the first winding and the second winding, the direction of the voltage generated across the second inductor is generated across the series circuit. The directions of the voltages are opposite to each other, and the voltages cancel each other. As a result, the voltage Vo on the second winding side between the first and second conductive lines is smaller than the voltage Vi applied to the first winding side. Conversely, when the normal mode voltage Vo is applied to the second winding side, the voltage Vi on the first winding side between the first and second conductive lines is the same as described above. Becomes smaller than the voltage Vo applied to the second winding side.
Thus, noise is satisfactorily suppressed over a wide frequency range by using the voltage generated in each inductor. Furthermore, in this noise suppression circuit, since each inductor is formed of the same common core, it is easier to reduce the size and manufacture than, for example, a configuration in which each core is separated and each inductor is independent and separated. It becomes easy to suppress the variation of the characteristic value at the stage. As a result, it is possible to obtain a favorable noise suppression effect while suppressing variations in the noise suppression effect.

In the noise suppression circuit according to the first aspect, a satisfactory noise suppression effect can be obtained particularly by satisfying the following conditions, which is preferable. That is, when the coupling coefficient between the first winding and the third winding is k2, and the coupling coefficient between the second winding and the third winding is k3, the values of the coupling coefficients k2 and k3 are respectively It is preferable that it is 0.5 or less.
In this case, it is more preferable that the values of the coupling coefficients k2 and k3 are the same, because it becomes easy to adjust the characteristic value of each circuit element so as to obtain a desired noise suppression effect.

Also, satisfying the following conditions is preferable because a good noise suppression effect can be obtained. That is, the self-inductance of the third winding is L3, the mutual inductance between the first and second windings is M1, and the mutual inductance between the first and third windings is When the inductance is M2 and the mutual inductance between the second winding and the third winding is M3, it is preferable that the following condition is satisfied.
L3 ≧ M1 + M2-M3

Moreover, regarding the winding method of each winding, satisfying the following conditions is preferable because a good noise suppressing effect can be obtained. That is, in the core, the third winding is wound at a position different from the first and second windings, and the magnetic flux generated by the third winding at each winding position is the first and second windings. It is preferable that the coil is wound in the opposite direction to the magnetic flux generated by the winding.
In particular, if the core is divided into a plurality, the first and second windings, and the third winding, it is preferable that he wound so as to span each of the divided core .

A noise suppression circuit according to a second aspect of the present invention is a circuit that suppresses common mode noise propagating through the first and second conductive lines in the same phase, and is inserted in series in the first conductive line. First and second windings, a third winding connected in series, and a first capacitor, one end of which is connected between the first winding and the second winding. The first series circuit with the other end grounded, the fourth and fifth windings inserted in series in the second conductive line, the sixth winding and the second connected in series, A second series circuit having one end connected between the fourth winding and the fifth winding and the other end grounded, the first and second windings, and the second 3 windings, and fourth and fifth windings, and a common core around which the sixth winding is wound .

  Here, one end of the first capacitor of the first series circuit is connected between the first winding and the second winding, and one end of the second capacitor of the second series circuit is connected to the first winding. 4 and the fifth winding, and the third winding of the first series circuit and the sixth winding of the second series circuit are shared, and the common One end of the converted winding may be connected to the other end of each capacitor of the first and second series circuits, and the other end may be grounded. The common winding may be wound around the same common core together with the first and second windings and the fourth and fifth windings.

In the noise suppression circuit according to the second aspect of the present invention, the first and second windings, the third winding, and the common core around which the first and second windings are wound , the first and second windings in each winding portion. Two inductors as well as a third inductor are formed. Similarly, the fourth and fifth windings and the sixth winding are wound around the same common core, and the fourth and fifth inductors and the sixth inductor are formed in each winding portion. Since each inductor is formed of the same common core, it is magnetically coupled to each other.
Here, when a common mode voltage Vi is applied to the first winding side between the first conductive line and the ground, the same phase is also applied to the fourth winding side between the second conductive line and the ground. A common mode voltage Vi is applied. The voltage Vi applied between the first conductive line and the ground is divided by the first inductor and the third inductor of the first series circuit, and the first inductor is connected to both ends of the first inductor and the first inductor. A predetermined voltage in the same direction is generated between both ends of the series circuit. Since the first inductor and the second inductor are formed of the same common core and are magnetically coupled to each other, both ends of the second inductor are generated according to a predetermined voltage generated between both ends of the first inductor. A predetermined voltage is also generated between them. Since one end of the first series circuit is connected between the first winding and the second winding, the direction of the voltage generated between both ends of the second inductor depends on the first series circuit. The direction of the voltage generated between both ends of the first and second voltages is opposite to each other, and these voltages cancel each other. As a result, the voltage Vo on the second winding side between the first conductive line and the ground is smaller than the voltage Vi applied to the first winding side. On the contrary, when the common mode voltage Vo is applied to the second winding side, the voltage Vi on the first winding side between the first conductive line and the ground is the same as described above. The voltage Vo is smaller than the voltage Vo applied to the second winding side.
Similarly, the voltage Vi applied to the fourth winding side between the second conductive line and the ground is divided by the fourth inductor and the sixth inductor of the second series circuit, A predetermined voltage in the same direction is generated between both ends of the inductor 4 and between both ends of the second series circuit. Since the fourth inductor and the fifth inductor are formed of the same common core and are magnetically coupled to each other, both ends of the fifth inductor are determined according to a predetermined voltage generated between both ends of the fourth inductor. A predetermined voltage is also generated between them. Since one end of the second series circuit is connected between the fourth winding and the fifth winding, the direction of the voltage generated between both ends of the fifth inductor depends on the second series circuit. The direction of the voltage generated between both ends of the first and second voltages is opposite to each other, and these voltages cancel each other. As a result, the voltage Vo on the fifth winding side between the second conductive line and the ground is smaller than the voltage Vi applied to the fourth winding side. Conversely, when the common mode voltage Vo is applied to the fifth winding side, the voltage Vi on the fourth winding side between the second conductive line and the ground is the same as described above. The voltage Vo is smaller than the voltage Vo applied to the fifth winding side.
Thus, noise is satisfactorily suppressed over a wide frequency range by using the voltage generated in each inductor. Furthermore, in this noise suppression circuit, since each inductor is formed of the same common core, for example, it is easier to reduce the size and manufacture than a case where each core is separated and each inductor is separated and separated. It becomes easy to suppress the variation of the characteristic value at the stage. As a result, it is possible to obtain a favorable noise suppression effect while suppressing variations in the noise suppression effect.

The noise suppression circuit according to the second aspect is preferable because a satisfactory noise suppression effect can be obtained by satisfying the following conditions. That is, when the coupling coefficient between the first winding and the third winding is k2, and the coupling coefficient between the second winding and the third winding is k3, the values of the coupling coefficients k2 and k3 are respectively It is preferable that it is 0.5 or less. Similarly, when the coupling coefficient between the fourth winding and the sixth winding is k5 and the coupling coefficient between the fifth winding and the sixth winding is k6, the values of the coupling coefficients k5 and k6 are as follows. Each is preferably 0.5 or less.
In this case, furthermore, if the values of the coupling coefficients k2 and k3 are the same as each other, and the values of the coupling coefficients k5 and k6 are the same as each other, Since it becomes easy to adjust the characteristic value of a circuit element, it is more preferable.

Also, satisfying the following conditions is preferable because a good noise suppression effect can be obtained. That is, the self-inductance of the third winding is L3, the mutual inductance between the first and second windings is M1, and the mutual inductance between the first and third windings is When the inductance is M2 and the mutual inductance between the second winding and the third winding is M3, it is preferable that the following condition is satisfied.
L3 ≧ M1 + M2-M3
Similarly, the self-inductance of the sixth winding is L6, the mutual inductance between the fourth and fifth windings is M4, and between the fourth and sixth windings. When the mutual inductance is M5 and the mutual inductance between the fifth winding and the sixth winding is M6, it is preferable that the following condition is satisfied.
L6 ≧ M4 + M5-M6

Moreover, regarding the winding method of each winding, satisfying the following conditions is preferable because a good noise suppressing effect can be obtained. That is, the third winding is wound at different positions of the core with respect to the first and second windings, and the magnetic flux generated by the third winding at each winding position is the first and second windings. It is preferably wound so as to be opposite to the magnetic flux generated by the wire. Similarly, the sixth winding is wound at different positions of the core with respect to the fourth and fifth windings, and the magnetic flux generated by the sixth winding at the respective winding positions is the fourth and fifth. It is preferable that the coil is wound in the opposite direction to the magnetic flux generated by the winding.
In particular, when the core is divided into a plurality of parts, the first and second windings, the third winding, the fourth and fifth windings, and the sixth winding are divided. it is preferable that he wound so as to span each of the cores.

  According to the noise suppression circuit of the first aspect of the present invention, one end of the series circuit including the third winding is connected to the first winding and the second winding inserted in series with each other on the first conductive line. The other end is connected to the second conductive wire, and each winding is wound around the same common core to form a plurality of inductors. Normal mode noise can be suppressed well. In particular, since each inductor is formed of the same common core, for example, compared to a case where each core is separated and each inductor is independent and separated, it is easy to downsize and variation in characteristic values at the manufacturing stage. And a good noise suppression effect can be obtained.

  According to the noise suppression circuit of the second aspect of the present invention, the first winding in which one end of the first series circuit including the third winding is inserted into the first conductive line in series with each other. And the other end of the second series circuit including the sixth winding are inserted in series with each other in the second conductive line. In addition to connecting between the fourth winding and the fifth winding, the other end is grounded, and each winding is wound around the same common core to form a plurality of inductors. Common mode noise can be satisfactorily suppressed over a range. In particular, since each inductor is formed of the same common core, for example, compared to a case where each core is separated and each inductor is independent and separated, it is easy to downsize and variation in characteristic values at the manufacturing stage. And a good noise suppression effect can be obtained.

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

[First Embodiment]
First, the noise suppression circuit according to the first embodiment of the present invention will be described. The noise suppression circuit according to the present embodiment is a circuit that suppresses normal mode noise that is transmitted through two conductive lines and causes a potential difference between the conductive lines.

  1A and 1B show first and second configuration examples of a noise suppression circuit according to the present embodiment. Hereinafter, the first configuration example of FIG. 1A will be basically described. This noise suppression circuit includes a pair of terminals 1A and 1B, another pair of terminals 2A and 2B, a first conductive line 3 connecting the terminals 1A and 2A, and a second connecting the terminals 1B and 2B. The conductive wire 4 is provided. The noise suppression circuit also includes first and second windings 11 and 12 inserted in series with each other on the first conductive wire 3, and one end of the first winding 11 and the second winding 12. And a series circuit 5 having the other end connected to the second conductive line 4. The series circuit 5 includes a third winding 13 and a capacitor C1 connected in series with each other.

  The noise suppression circuit further includes a core 10 around which the first and second windings 11 and 12 and the third winding 13 are wound in common. The first and second windings 11 and 12 and the third winding 13 and the core 10 on which they are wound in common, the first and second inductors L1 and L2 and the second windings in each winding portion. 3 inductors L3 are formed. Since each inductor is formed of the same common core 10, it is magnetically coupled to each other. The inductances of the first and second inductors L1, L2 are preferably the same value.

  2 (A) and 2 (B), the first and second windings 11 and 12 and the third winding 13 are shown as comparative examples to the configuration examples of FIGS. 1 (A) and 1 (B). Shows an equivalent circuit in a case where is configured to be wound separately on different cores.

  One end of the capacitor C <b> 1 is connected between the first and second windings 11 and 12, and the other end is connected to one end of the third winding 13. The other end of the third winding 13 is connected to the second conductive line 4. The capacitor C1 functions as a high-pass filter that allows a normal mode signal having a frequency equal to or higher than a predetermined value to pass through the series circuit 5.

  As shown in FIG. 1B, the positional relationship between the third winding 13 and the capacitor C1 in the series circuit 5 may be reversed. That is, one end of the third winding 13 may be connected between the first and second windings 11, 12 and the other end of the capacitor C 1 may be connected to the second conductive line 4.

  In this noise suppression circuit, the coupling coefficient between the first winding 11 and the third winding 13 is k2 and the coupling coefficient between the second winding 12 and the third winding 13 is shown in FIG. When k3 is set to k3, it is preferable that the coupling coefficients k2 and k3 are set to be smaller than 0.5 respectively. That is, it is preferable that the magnetic coupling is weak. Further, it is more preferable that the values of the coupling coefficients k2 and k3 are the same value because the characteristic values of the respective circuit elements can be easily adjusted so as to obtain a desired noise suppression effect. On the other hand, the coupling coefficient k1 between the first winding 11 and the second winding 12 is preferably set to a larger value than k2 and k3. That is, it is preferable that the magnetic coupling is strong.

The self-inductance of the third winding 13 alone is L3, the mutual inductance between the first winding 11 and the second winding 12 is M1, the first winding 11 and the third winding When the mutual inductance between the windings 13 is M2 and the mutual inductance between the second winding 12 and the third winding 13 is M3, it is preferable that the following conditions are satisfied.
L3 ≧ M1 + M2-M3
The basis for these being preferable conditions will be described later.

  FIGS. 3A, 3B, and 4 show a specific example of the configuration of the core 10 and how to wind each winding. By adopting these configurations, it is easy to satisfy the preferable conditions. As described above, the values of the coupling coefficients k2 and k3 between the third winding 13 and the first and second windings 11 and 12 are preferably set to be smaller than 0.5, respectively. 10, the third winding 13 is preferably wound at a different position from the first and second windings 11 and 12. Further, since it is preferable that the coupling coefficients k2 and k3 have the same value, for example, the first and second windings 11 and 12 are positioned symmetrically with respect to the third winding 13. It is preferably wound.

  Specifically, for example, as shown in FIG. 3A, in the 8-shaped core 10, the third winding 13 is wound around the left pillar portion in the left portion 10L, and the right portion 10R is wound. The first and second windings 11 and 12 are preferably wound around the upper and lower pillar portions in FIG. Further, as shown in FIG. 3B, both the first and second windings 11 and 12 may be wound around the right column portion in the right portion 10R. In these cases, in order to keep the coupling between the third winding 13 and the first and second windings 11 and 12 low, the third winding 13 is generated at each winding position as shown in the figure. It is preferable that the magnetic flux Φ2 is wound in a direction opposite to the magnetic flux Φ1 generated by the first and second windings 11 and 12. Thus, in the state shown in the figure, a counterclockwise magnetic path is formed by the magnetic flux Φ2 of the third winding 13, and conversely, a clockwise rotation is generated by the magnetic flux Φ1 of the first and second windings 11 and 12. A magnetic path is formed. In such a case, a common magnetic path is formed in the same direction by the magnetic fluxes Φ1 and Φ2 in the central column portion, but it is not preferable to wind each winding around this portion. That is, it is preferable that each winding is wound around a portion where a common magnetic path is not formed.

  Further, when the core 10 is divided into a plurality of parts, the first and second windings 11 and 12 and the third winding 13 are commonly used so as to straddle each of the divided cores. It is preferably wound. Specifically, for example, as shown in FIG. 4, when the core 10 is divided into two E-shaped cores 10 </ b> A and 10 </ b> B, each winding is formed so as to straddle the divided surface 10 </ b> C. It is preferably wound. In the example of FIG. 4, the third winding 13 is wound so as to straddle the dividing surface 10 </ b> C in the left pillar portion in the left portion 10 </ b> L of each of the two cores 10 </ b> A and 10 </ b> B. In addition, the first and second windings 11 and 12 are wound in an overlapping manner so as to straddle the dividing surface 10C in the right column portion in the right portion 10R of each of the two cores 10A and 10B.

  In addition, the shape of the core 10 and the winding method of each winding are not limited to those shown in the drawings, and other configurations can be adopted. The core 10 may be divided into three or more. Also, the polarity of each winding and the direction of winding may be reversed from those shown in the figure.

  Next, the operation of this noise suppression circuit will be described.

First, the principle of the noise suppression operation by this noise suppression circuit will be described with reference to FIG. It is assumed that the inductances of the first and second inductors L1 and L2 are the same value, and the impedance of the capacitor C1 is low enough to be ignored. In this case, when the normal mode voltage Vi is applied between the terminals 1A and 1B (the first winding 11 side between the first and second conductive lines 3 and 4) as shown in FIG. The voltage Vi is divided by the first inductor L1 and mainly the third inductor L3 of the series circuit 5, and is in the same direction between both ends of the first inductor L1 and between both ends of the third inductor L3. Predetermined voltages V1 and V3 are generated. Note that the arrow in the figure indicates that the potential ahead is higher. Since the first inductor L1 and the second inductor L2 are formed of the same common core 10 and are magnetically coupled to each other, the second inductor L1 and the second inductor L2 are coupled with each other according to the voltage V1 generated across the first inductor L1. The same voltage V2 as the voltage V1 is generated between both ends of the inductor L2. Since one end of the series circuit 5 is connected between the first winding 11 and the second winding 12, the direction of the voltage V2 generated between both ends of the second inductor L2 is the third The direction of the voltage V3 generated between both ends of the inductor L3 is opposite to each other, and these voltages cancel each other. As a result, the voltage Vo between the terminals 2A and 2B (the second winding side between the first and second conductive lines 3 and 4) is smaller than the voltage Vi applied between the terminals 1A and 1B. Conversely, when the normal mode voltage Vo is applied between the terminals 2A and 2B, the voltage Vi between the terminals 1A and 1B is equal to the voltage Vo applied between the terminals 2A and 2B in the same manner as described above. Smaller than.
In this way, by using the voltage generated in each inductor, either normal mode noise is applied between terminals 1A and 1B or normal mode noise is applied between terminals 2A and 2B. Even in this case, it is possible to satisfactorily suppress normal mode noise over a wide frequency range.

Here, the first and second windings 11 and 12 and the third winding 13 (the first and second inductors L1 and L2 and the third inductor L3) in consideration of the coupling between the windings. The self-inductances L1 ′, L2 ′, and L3 ′ are defined as follows. In addition, as shown in FIG. 5, let the mutual inductance between each winding be M1, M2, and M3. Further, the self-inductances of the first and second windings 11 and 12 and the third winding 13 are L1, L2, and L3.
L1 ′ = L1 + M1-M2-M3
L2 ′ = L2 + M1 + M2 + M3
L3 '= L3-M1-M2 + M3

  FIG. 8 is a graph showing the calculation results obtained by changing the value of the inductance L3 ′ as L3 ′ <0, L3 ′ = 0, L3 ′> 0 as the attenuation characteristic in the noise suppression circuit. The horizontal axis represents frequency (Hz), and the vertical axis represents attenuation (dB). A representative value of L3 ′ <0 was −10 (μH), and a representative value of L3 ′> 0 was 10 (μH). Here, since L3 'is expressed as described above, it can be adjusted, for example, by changing the value of the self-inductance L3 of the third winding 13 alone. As an example, FIG. 7 shows circuit values when adjustment is performed so that L3 ′ = − 10, 0, 10 by changing the value of L3. C1 indicates the capacitance of the capacitor C1. k1, k2, and k3 are coupling coefficients between the windings as shown in FIG.

From the result of FIG. 8, when L3 ′ = 0, a good attenuation characteristic is obtained in which the attenuation amount becomes sufficiently large as the frequency becomes higher. When L3 ′> 0, an attenuation pole is formed on the low frequency side, and there is a band where the attenuation is partially larger than when L3 ′ = 0. When L3 ′ <0, the amount of attenuation is particularly insufficient on the high frequency side compared to when L3 ′ = 0. Considering the use as a noise filter, the performance is preferable when L3 ′ ≧ 0.
Here, since L3 ′ = L3−M1−M2 + M3, a preferable condition in terms of performance is
L3 ≧ M1 + M2-M3
It becomes.

  Next, the operation and effect of winding each winding around the same common core 10 will be described. For example, the characteristic value of each circuit element may vary from the design value (ideal value) due to the difference between lots in the actual manufacturing stage. FIG. 9 shows the result of calculating the characteristic value of each circuit element on the assumption that the magnetic permeability of the core 10 varies with respect to the design value. Here, when variation occurs in the noise suppression circuit according to the present embodiment of FIG. 1A (variation consideration, core integration), and variation occurs in the noise suppression circuit of the comparative example of FIG. The case (variation consideration, core separation) was calculated. When the magnetic permeability changes, the self-inductances L1, L2, and L3 change, so this value is changed from the ideal value. FIG. 10 is a graph showing the results of calculating the attenuation characteristics in each case.

  In the case of the noise suppression circuit of the comparative example of FIG. 2 (A), since the cores 10 are separate for the first and second windings 11 and 12 and the third winding 13, It is conceivable that the values change in the opposite directions in the cores. Therefore, in the case of the noise suppression circuit of the comparative example of FIG. 2A, the values of L1 and L2 are deviated by + 25% from the design value, and the values of L3 are calculated by deviating by -25%. . On the other hand, in the noise suppression circuit according to the present embodiment, since the same core 10 is used in each winding, the values of L1, L2, and L3 change in the same direction. Therefore, this noise suppression circuit was calculated assuming that the values of L1, L2, and L3 all deviated by + 25% from the design values.

  As can be seen from FIG. 9, in the case of the noise suppression circuit of the comparative example, a shift occurs in the value of L3 ′, but in the case of the noise suppression circuit according to the present embodiment, a shift occurs in the value of L3 ′. Not. As already described with reference to FIGS. 7 and 8, there is a difference in the attenuation characteristic due to the difference in L3 ′. As can be seen from the attenuation characteristic in FIG. 10, in the case of the noise suppression circuit of the comparative example (core In the case of separation, the attenuation characteristic is deteriorated with respect to the ideal state. However, in the case of the noise suppression circuit according to the present embodiment (core integrated), there is almost no difference in attenuation characteristic. As described above, in the noise suppression circuit according to the present embodiment, each winding is applied to the same core 10, so that the magnetic permeability variation in the core between the windings can be reduced as compared with the configuration in which the cores are separated. It can be lost. Thereby, deterioration of the attenuation characteristic can be prevented. Further, the unstable coupling between the windings due to the difference in the component arrangement can be eliminated, and a stable attenuation characteristic can be obtained.

  Next, in this noise suppression circuit, the change in characteristics due to the difference between the coupling coefficients k2 and k3 was calculated. FIG. 11 shows the calculation conditions. Here, in particular, when the values of the coupling coefficients k2 and k3 are equal to each other, the attenuation characteristics are calculated when k2, k3 = 0, 0.1, 0.3, 0.5, 0.7, and 0.9 are changed. did.

FIG. 12 and FIG. 13 show the calculation results. FIG. 12 shows the attenuation value particularly at 1 MHz. As the values of k2 and k3 increase, the attenuation characteristic deteriorates. Here, in the case of electric power, if the value is deteriorated by 3 dB, the electric power is increased approximately twice. In the case of voltage, a deterioration of the value by 3 dB increases the voltage by about 1.4 times. Since the performance as a noise filter is often considered in terms of voltage, it is not preferable to deteriorate by 3 dB or more. Therefore, the preferable conditions for the values of k2 and k3 are:
0.5 ≧ k2, k3
It becomes.

As described above, according to the present embodiment, the first and second windings 11 and 12 and the third winding 13 are wound around the same common core 10 to form each inductor. Therefore, for example, as compared with a case where the cores are separated and the inductors are configured to be independent and separated, it is easy to reduce the size and suppress variation in characteristic values in the manufacturing stage. In addition, variations in characteristic values due to differences in component arrangement can be easily suppressed. As a result, it is possible to obtain a favorable noise suppression effect while suppressing variations in the noise suppression effect. In particular, as compared with the case where the cores 10 are separately provided, it is possible to eliminate the deviation from the optimum value of the attenuation characteristics due to the variation in magnetic permeability. Further, since the matching between the first and second inductors L1 and L2 and the third inductor L3 is not necessary, unnecessary adjustment is not required.
[Second Embodiment]

  Next, a noise suppression circuit according to a second embodiment of the present invention will be described. The noise suppression circuit according to the present embodiment is a circuit that suppresses common mode noise that propagates through the first and second conductive lines in the same phase.

FIGS. 14A and 14B show first and second configuration examples of the noise suppression circuit according to the present embodiment. Note that components that are substantially the same as those of the noise suppression circuit (FIGS. 1A and 1B) in the first embodiment are denoted by the same reference numerals. Hereinafter, the first configuration example in FIG. 14A will be basically described. As in the noise suppression circuit of FIG. 1A, this noise suppression circuit has first and second windings 11 and 12 inserted in series in the first conductive wire 3 and one end of the first suppression line. A first series circuit 5 connected between the winding 11 and the second winding 12 is provided. The first series circuit 5 includes a third winding 13 and a first capacitor C1 connected in series with each other. In the noise suppression circuit of FIG. 1A, the other end of the first series circuit 5 is connected to the second conductive line 4, but in this noise suppression circuit, the other end of the first series circuit 5 is grounded. ing.
The noise suppression circuit also includes the same circuit components on the second conductive line 4 side as on the first conductive line 3 side. That is, the fourth and fifth windings 14 and 15 inserted in series in the second conductive wire 4 and one end thereof is connected between the fourth winding 14 and the fifth winding 15. And a second series circuit 6. The second series circuit 6 includes a sixth winding 16 and a second capacitor C2 that are connected in series with each other. The other end of the second series circuit 6 is grounded.

  The noise suppression circuit further includes the first and second windings 11 and 12, the third winding 13, the fourth and fifth windings 14 and 15, and the sixth winding 16 in common. The core 10 is wound around. On the first conductive wire 3 side, the first and second windings 11 and 12, the third winding 13, and the core 10 on which they are wound in common, the first and second windings in each winding portion. Two inductors L1, L2 and a third inductor L3 are formed. Similarly, on the second conductive wire 4 side, the fourth and fifth windings 14 and 15 and the sixth winding 16 and the core 10 around which they are wound in common, the fourth winding in each winding portion. The fifth inductors L4 and L5 and the sixth inductor L6 are formed. Since each inductor is formed of the same common core 10, it is magnetically coupled to each other. The inductances of the first and second inductors L1, L2 are preferably the same value. Similarly, the inductances of the fourth and fifth inductors L4 and L5 are preferably the same value. The first and second inductors L1 and L2 and the fourth and fifth inductors L4 and L5 cooperate to suppress common mode noise.

  15A and 15B, the third and sixth windings 13 and 16 are separated from the other windings as a comparative example to the configuration examples of FIGS. 14A and 14B. The equivalent circuit in the case of a configuration in which the core is separated and wound is shown.

  The first capacitor C1 has one end connected between the first and second windings 11 and 12 and the other end connected to one end of the third winding 13. The other end of the third winding 13 is grounded. The second capacitor C2 has one end connected between the fourth and fifth windings 14 and 15 and the other end connected to one end of the sixth winding 16. The other end of the sixth winding 16 is grounded. The first and second capacitors C1 and C2 function as a high-pass filter that allows a common mode signal having a frequency equal to or higher than a predetermined value to pass through the first and second series circuits 5 and 6.

  As shown in FIG. 14B, the positional relationship between the third winding 13 and the first capacitor C1 in the first series circuit 5 may be reversed. That is, one end of the third winding 13 may be connected between the first and second windings 11 and 12 and the other end of the capacitor C1 may be grounded. Similarly, the positional relationship between the sixth winding 16 and the second capacitor C2 in the second series circuit 6 may be reversed. That is, one end of the sixth winding 16 may be connected between the fourth and fifth windings 14 and 15 and the other end of the second capacitor C2 may be grounded.

In this noise suppression circuit, the coupling coefficient between the first winding 11 and the third winding 13 is k2 and the coupling coefficient between the second winding 12 and the third winding 13 is shown in FIG. When k3 is set to k3, it is preferable that the values of the coupling coefficients k2 and k3 are set to be slightly smaller than 0.5 for the same reason as in the configuration example of FIG. That is, it is preferable that the magnetic coupling is weak. Further, it is more preferable that the values of the coupling coefficients k2 and k3 are the same value because the characteristic values of the respective circuit elements can be easily adjusted so as to obtain a desired noise suppression effect. On the other hand, the coupling coefficient k1 between the first winding 11 and the second winding 12 is preferably set to a larger value than k2 and k3. That is, it is preferable that the magnetic coupling is strong.
In addition to this, for the same reason, the coupling coefficient between the fourth winding 14 and the sixth winding 16 is k5, and the coupling coefficient between the fifth winding 15 and the sixth winding 16 is k6. In this case, it is preferable that the values of the coupling coefficients k5 and k6 are 0.5 or less, respectively. It is more preferable that the values of the coupling coefficients k5 and k6 are the same. On the other hand, the coupling coefficient k4 between the fourth winding 14 and the fifth winding 15 is preferably set to a larger value than k5 and k6.

Further, for the same reason as in the configuration example of FIG. 1A described above, the self-inductance of the third winding 13 alone is L3, and the first winding 11 and the second winding 12 are not connected. The mutual inductance between the first winding 11 and the third winding 13 is M2, and the mutual inductance between the second winding 12 and the third winding 13 is M3. It is preferable that the following conditions are satisfied.
L3 ≧ M1 + M2-M3
In addition to this, for the same reason, the self-inductance of the sixth winding 16 alone is L6, and the mutual inductance between the fourth winding 14 and the fifth winding 15 is M4, When the mutual inductance between the winding 14 and the sixth winding 16 is M5 and the mutual inductance between the fifth winding 15 and the sixth winding 16 is M6, the following conditions are satisfied. It is preferable.
L6 ≧ M4 + M5-M6

FIGS. 16A, 16B, and 17 show specific examples of the configuration of the core 10 and how to wind each winding. By adopting these configurations, it is easy to satisfy the preferable conditions. As described above, the values of the coupling coefficients k2 and k3 between the third winding 13 and the first and second windings 11 and 12 are preferably set to be smaller than 0.5, respectively. 10, the third winding 13 is preferably wound at a different position from the first and second windings 11 and 12. Similarly, the sixth winding 16 is preferably wound at a different position from the fourth and fifth windings 14 and 15.
In order to suppress common mode noise satisfactorily, the windings 11, 12, 13 on the first conductive wire 3 side and the windings 14, 15, 16 on the second conductive wire 4 side are symmetrical with each other. It is preferable that the wire is wound at a proper position. The first and second windings 11 and 12 and the fourth and fifth windings 14 and 15 are magnetically coupled to each other so as to cooperate and suppress common mode noise by being wound around the common core 10. Is bound to. That is, the windings are wound around the core 10 in such a direction that the magnetic fluxes induced in the core 10 are canceled by each other when the normal mode current flows through them. preferable. The windings and the core 10 preferably constitute a common mode choke coil that suppresses common mode noise and passes a normal mode signal. The inductors L21, L22, L24, and L25 only have to have the same polarity, and the polarity directions of all the inductors may be opposite to those illustrated.

  Specifically, for example, as shown in FIG. 16A, in the 8-shaped core 10, the third winding 13 is wound on the upper side of the left column portion in the left portion 10L, and the The first and second windings 11 and 12 are wound around the upper column portion of the right portion 10R, and symmetrically, the sixth winding 16 is wound below the left column portion in the left portion 10L. The fourth and fifth windings 14 and 15 are preferably wound around the lower pillar portion of the right portion 10R. Further, as shown in FIG. 16B, the third winding 13 is wound around the upper column portion in the left portion 10L, and the sixth winding 16 is wound around the lower column portion. good. In these cases, in order to keep the coupling between the third winding 13 and the first and second windings 11 and 12 low, the third winding 13 is generated at each winding position as shown in the figure. It is preferable that the magnetic flux Φ2 is wound in a direction opposite to the magnetic flux Φ1 generated by the first and second windings 11 and 12. Thus, in the state shown in the figure, a counterclockwise magnetic path is formed by the magnetic flux Φ2 of the third winding 13, and conversely, a clockwise rotation is generated by the magnetic flux Φ1 of the first and second windings 11 and 12. A magnetic path is formed. In such a case, a common magnetic path is formed in the same direction by the magnetic fluxes Φ1 and Φ2 in the central column portion, but it is not preferable to wind each winding around this portion. That is, it is preferable that each winding is wound around a portion where a common magnetic path is not formed. The same applies to the sixth winding 16 and the fourth and fifth windings 14 and 15.

  Further, when the core 10 is divided into a plurality of parts, the first and second windings 11 and 12, the third winding 13, the fourth and fifth windings 14 and 15, and the sixth The winding 16 is preferably wound in common so as to straddle each of the divided cores. Specifically, for example, as shown in FIG. 17, when the core 10 is divided into two E-shaped cores 10 </ b> A and 10 </ b> B, each winding is formed so as to straddle the divided surface 10 </ b> C. It is preferably wound. In the example of FIG. 17, the third winding wire 13 and the sixth winding wire 16 are wound so as to straddle the dividing surface 10 </ b> C in the left pillar portion in the left portion 10 </ b> L of each of the two cores 10 </ b> A and 10 </ b> B. It has been. Further, the first and second windings 11 and 12 and the fourth and fifth windings straddle the dividing surface 10C in the right column portion in the right portion 10R of each of the two cores 10A and 10B. 14 and 15 are overlapped and wound.

  In addition, the shape of the core 10 and the winding method of each winding are not limited to those shown in the drawings, and other configurations can be adopted. The core 10 may be divided into three or more. Also, the polarity of each winding and the direction of winding may be reversed from those shown in the figure.

  Next, the operation of this noise suppression circuit will be described.

First, the principle of the noise suppression operation by this noise suppression circuit will be described with reference to FIG. It is assumed that the inductances of the first and second inductors L1 and L2 are the same value, and the impedance of the first capacitor C1 is low enough to be ignored. Similarly, the inductances of the fourth and fifth inductors L4 and L5 are set to the same value, and the impedance of the second capacitor C2 is low enough to be ignored.
First, the case where the common mode voltage Vi is applied to the terminals 1A and 1B will be described. In this case, when a common mode voltage Vi is applied to the first winding 11 side between the first conductive wire 3 and the ground, the fourth winding 14 side is also connected between the second conductive wire 4 and the ground. A common-mode voltage Vi having the same phase is applied to. The voltage Vi applied between the first conductive line 3 and the ground is divided by the first inductor L1 and mainly the third inductor L3 of the first series circuit 5, and the both ends of the first inductor L1. And predetermined voltages V1 and V3 in the same direction are generated between the both ends of the first series circuit 5, respectively. Note that the arrow in the figure indicates that the potential ahead is higher. Since the first inductor L1 and the second inductor L2 are formed of the same common core 10 and are magnetically coupled to each other, the first inductor L1 and the second inductor L2 are changed according to a predetermined voltage V1 generated between both ends of the first inductor L1. The same voltage V2 as the voltage V1 is generated between both ends of the second inductor L2. Since one end of the first series circuit 5 is connected between the first winding 11 and the second winding 12, the direction of the voltage V2 generated between both ends of the second inductor L2 is The direction of the voltage V3 generated between both ends of the first series circuit 5 is opposite, and these voltages cancel each other. As a result, the voltage Vo on the second winding 12 side between the first conductive wire 3 and the ground is smaller than the voltage Vi applied to the first winding 11 side.

  Similarly, the voltage Vi applied to the fourth winding 14 side between the second conductive wire 4 and the ground is mainly generated by the fourth inductor L4 and the sixth inductor L6 of the second series circuit 6. The divided voltages generate predetermined voltages V1 and V3 in the same direction between both ends of the fourth inductor L4 and between both ends of the second series circuit 6, respectively. Since the fourth inductor L4 and the fifth inductor L5 are formed of the same common core 10 and are magnetically coupled to each other, the fourth inductor L4 and the fifth inductor L5 are in accordance with a predetermined voltage V1 generated between both ends of the fourth inductor L4. The same voltage V2 as the voltage V1 is generated between both ends of the five inductors L5. Since one end of the second series circuit 6 is connected between the fourth winding 14 and the fifth winding 15, the direction of the voltage V2 generated between both ends of the fifth inductor L5 is The direction of the voltage V3 generated between both ends of the second series circuit 6 is opposite, and these voltages cancel each other. As a result, the voltage Vo on the fifth winding 15 side between the second conductive wire 4 and the ground is smaller than the voltage Vi applied to the fourth winding 14 side.

  In this circuit, when the common mode voltage Vo is applied to the terminals 2A and 2B, the common mode voltage Vi generated at the terminals 1A and 1B is applied to the terminals 2A and 2B in the same manner as described above. It becomes smaller than the applied common mode voltage Vo. As described above, by using the voltage generated in each inductor, the common mode noise is applied to the terminals 1A and 1B and the common mode noise is applied to the terminals 2A and 2B. Common mode noise can be satisfactorily suppressed over a wide frequency range.

Here, as in the first embodiment, the first and second windings 11 and 12 and the third winding 13 (first and second inductors L1) in consideration of the coupling between the windings. , L2 and the self-inductances L1 ′, L2 ′, L3 ′ of the third inductor L3) are defined as follows. As shown in FIG. 18, the mutual inductance between the windings is M1, M2, and M3. Further, the self-inductances of the first and second windings 11 and 12 and the third winding 13 are L1, L2, and L3.
L1 ′ = L1 + M1-M2-M3
L2 ′ = L2 + M1 + M2 + M3
L3 '= L3-M1-M2 + M3

Similarly, the fourth and fifth windings 14 and 15 and the sixth winding 16 (the fourth and fifth inductors L4 and L5 and the sixth inductor L6) in consideration of the coupling between the windings. The self-inductances L4 ′, L5 ′, and L6 ′ are defined as follows. As shown in FIG. 18, the mutual inductance between the windings is M4, M5, and M6. The self-inductances of the fourth and fifth windings 14 and 15 and the sixth winding 16 are L4, L5, and L6.
L4 '= L4 + M4-M5-M6
L5 ′ = L5 + M4 + M5 + M6
L6 '= L6-M4-M5 + M6

For the same reason as described with reference to FIG. 7 and FIG. 8 in the first embodiment, the noise suppression circuit according to the present embodiment is also considered in terms of performance when considered to be used as a noise filter. Preferred is when L3 ′ ≧ 0 and L6 ′ ≧ 0, and the following conditions are obtained as preferred conditions.
L3 ≧ M1 + M2-M3
L6 ≧ M4 + M5-M6

  Further, for the same reason as described with reference to FIGS. 9 and 10 in the first embodiment, the same core 10 is provided with each winding in the noise suppression circuit according to the present embodiment. As a result, it is possible to eliminate variation in magnetic permeability in the core between the windings as compared with the configuration in which the cores are separated (FIGS. 15A and 15B). Thereby, deterioration of the attenuation characteristic can be prevented. Further, the unstable coupling between the windings due to the difference in the component arrangement can be eliminated, and a stable attenuation characteristic can be obtained.

As described above, according to the second embodiment, the first and second windings 11 and 12, the third winding 13 and the fourth and fifth windings 14 and 15, and Since each inductor is formed by winding the sixth winding 16 around the same common core 10, for example, it is easier to reduce the size than when the cores are separated and the inductors are separated and separated. In addition, it is easy to suppress variations in characteristic values in the manufacturing stage. In addition, variations in characteristic values due to differences in component arrangement can be easily suppressed. As a result, it is possible to obtain a favorable noise suppression effect while suppressing variations in the noise suppression effect. In particular, as compared with the case where the cores 10 are separately provided, it is possible to eliminate the deviation from the optimum value of the attenuation characteristics due to the variation in magnetic permeability. Further, since the matching between the first and second inductors L1 and L2 and the third inductor L3 is not necessary, unnecessary adjustment is not required. Similarly, since the matching between the fourth and fifth inductors L4 and L5 and the sixth inductor L6 becomes unnecessary, unnecessary adjustment is not required.
<Modification of Second Embodiment>

  FIG. 20 shows a circuit configuration of a modification of the noise suppression circuit according to the present embodiment. In the noise suppression circuit according to this modification, the third winding 13 and the sixth winding 16 are shared in the circuit shown in FIG. The second windings 11 and 12 and the fourth and fifth windings 14 and 15 are wound around a common core 10. As a result, the third inductor L3 in the first series circuit 5 and the sixth inductor L6 in the second series circuit 6 are shared. One end of the common winding is connected to the other ends of the capacitors C1 and C2 in the first and second series circuits 5 and 6, and the other end is grounded. Hereinafter, in this modification, the common winding is referred to as a third winding 13, and the common inductor is referred to as a third inductor L3.

  In FIG. 23, as a comparative example with respect to the configuration example of FIG. 20, the common third winding 13 is separated and wound on a separate core from the other windings. An equivalent circuit is shown.

  Also in this modification, the same preferable conditions as in the circuit of FIG. 14A are satisfied with respect to the inductance of each winding and the coupling coefficient between the windings. That is, when the coupling coefficient between the third winding 13 and the first winding 11 is k2, and the coupling coefficient between the third winding 13 and the second winding 12 is k3, the coupling coefficients k2, k3. It is preferable that each of the values is set to a small value of 0.5 or less. It is more preferable that the values of the coupling coefficients k2 and k3 are the same. In addition, when the coupling coefficient between the fourth winding 14 and the third winding 13 is k5 and the coupling coefficient between the fifth winding 15 and the third winding 13 is k6, the coupling coefficient It is preferable that the values of k5 and k6 are 0.5 or less, respectively. It is more preferable that the values of the coupling coefficients k5 and k6 are the same. L3 and L6 are the same as described above.

  FIGS. 21A, 21B, and 22 show a specific example of the configuration of the core 10 in this modification and how to wind each winding. By adopting these configurations, it is easy to satisfy the preferable conditions. The preferred winding method is basically the same as that shown in FIGS. 16 (A), 16 (B) and FIG.

  Specifically, for example, as shown in FIG. 21 (A), in the 8-shaped core 10, a common third winding is formed at the center of the left pillar portion in the left portion 10L. 13 and the first and second windings 11 and 12 are wound around the upper column portion of the right portion 10R, and symmetrically, the fourth and fifth windings are wound around the lower column portion of the right portion 10R. It is good to wind the wires 14 and 15. In addition, as shown in FIG. 21B, the first and fourth windings 11 and 14 are wound around the upper column portion in the right portion 10R, and the second and fifth windings 12 are wound around the lower column portion. , 15 may be wound.

  For example, as shown in FIG. 17, when the core 10 is divided into two E-shaped cores 10 </ b> A and 10 </ b> B, each winding is wound so as to straddle the divided surface 10 </ b> C. It is preferable. In the example of FIG. 17, the common third winding 13 is wound so as to straddle the dividing surface 10 </ b> C in the left pillar portion in the left portion 10 </ b> L of each of the two cores 10 </ b> A and 10 </ b> B. . Further, the first and second windings 11 and 12 and the fourth and fifth windings straddle the dividing surface 10C in the right column portion in the right portion 10R of each of the two cores 10A and 10B. 14 and 15 are overlapped and wound.

  Also by the noise suppression circuit according to this modification, the same excellent noise suppression effect as that of the circuit of FIG. In particular, in this modification, since the third winding 13 and the sixth winding 16 are shared, the size can be further reduced.

  Note that the noise suppression circuit according to each embodiment includes means for reducing ripple voltage and noise generated by the power conversion circuit, noise on the power line in power line communication, and communication signals on the indoor power line are transmitted to the outdoor power line. It can be used as a means for preventing leakage.

  In addition, this invention is not limited to said each embodiment, A various change is possible. For example, the noise suppression circuit of the present invention may include a normal mode noise suppression circuit according to the first embodiment and a common mode noise suppression circuit according to the second embodiment.

It is a circuit diagram which shows the 1st and 2nd structural example of the noise suppression circuit which concerns on the 1st Embodiment of this invention. It is a circuit diagram of the comparative example with respect to the 1st and 2nd structural example of the noise suppression circuit which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of each winding in the noise suppression circuit which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of each coil | winding in case the core is divided | segmented. It is a figure for demonstrating the coupling relationship between each coil | winding. It is a circuit diagram for demonstrating the principle of operation of the noise suppression circuit which concerns on the 1st Embodiment of this invention. It is the figure which calculated and showed each circuit value when changing the self-inductance of the 3rd coil | winding part in the noise suppression circuit which concerns on the 1st Embodiment of this invention. In the noise suppression circuit which concerns on the 1st Embodiment of this invention, it is the figure which calculated and graphed the difference of the attenuation characteristic when changing the self-inductance of the 3rd coil | winding part. In the noise suppression circuit according to the first embodiment of the present invention, it is a diagram showing a calculated change in each circuit value when variation occurs in the self-inductance of each winding portion. In the noise suppression circuit which concerns on the 1st Embodiment of this invention, it is the figure which computed and calculated the attenuation characteristic when dispersion | variation arises in the self-inductance of each winding part. In the noise suppression circuit according to the first embodiment of the present invention, it is a diagram showing the difference in the characteristic value of each winding portion when the coupling coefficient between each winding is changed. It is the figure which calculated and showed the difference in the attenuation amount in 1 MHz when the coupling coefficient between each winding was changed in the noise suppression circuit which concerns on the 1st Embodiment of this invention. In the noise suppression circuit according to the first embodiment of the present invention, it is a graph calculated by calculating the difference in attenuation characteristics when the coupling coefficient between the windings is changed. It is a circuit diagram which shows the 1st and 2nd structural example of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a circuit diagram of the comparative example with respect to the 1st and 2nd structural example of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of each coil | winding in the 1st and 2nd structural example of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of each coil | winding in case the core is divided | segmented in the 1st and 2nd structural example. It is a figure for demonstrating the coupling relationship between each coil | winding. It is a circuit diagram for demonstrating the principle of operation of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the modification of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of each coil | winding in the modification of the noise suppression circuit which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of each coil | winding in case the core is divided | segmented in the noise suppression circuit which concerns on a modification. It is a circuit diagram of the comparative example with respect to the noise suppression circuit which concerns on a modification.

Explanation of symbols

  C1 ... 1st capacitor, C2 ... 2nd capacitor, L1 ... 1st inductor, L2 ... 2nd inductor, L3 ... 3rd inductor, L4 ... 4th inductor, L5 ... 5th inductor, L6 ... 6th inductor, 3 ... 1st conductive wire, 4 ... 2nd conductive wire, 5 ... Series circuit, 10 ... Core, 11 ... 1st winding, 12 ... 2nd winding, 13 ... 1st 3 windings, 14 ... 4th winding, 15 ... 5th winding, 16 ... 6th winding.

Claims (13)

A circuit that suppresses normal mode noise that is transmitted by first and second conductive lines and causes a potential difference between the conductive lines,
First and second windings inserted in series with each other in the first conductive line;
A third winding and a capacitor connected in series are included, one end is connected between the first winding and the second winding, and the other end is connected to the second conductive line. Series circuit,
A noise suppression circuit comprising: the first and second windings; and a common core around which the third winding is wound . When the coupling coefficient between the first winding and the third winding is k2, and the coupling coefficient between the second winding and the third winding is k3,
The noise suppression circuit according to claim 1, wherein the coupling coefficients k2 and k3 each have a value of 0.5 or less. The noise suppression circuit according to claim 2, wherein the coupling coefficients k2 and k3 have the same value. The self-inductance of the third winding is L3,
The mutual inductance between the first winding and the second winding is M1, the mutual inductance between the first winding and the third winding is M2, and the second winding. When the mutual inductance between the coil and the third winding is M3, the following condition is satisfied: L3 ≧ M1 + M2−M3
The noise suppression circuit according to any one of claims 1 to 3, wherein In the core, the third winding is wound at a position different from the first and second windings, and magnetic flux generated by the third winding at each winding position is the first and second windings. The noise suppression circuit according to any one of claims 1 to 4, wherein the noise suppression circuit is wound in a direction opposite to the magnetic flux generated by the second winding. The core is composed of a plurality of divided cores,
Said first and second windings, and the third winding, any one of claims 1 to 5, characterized in that it he wound so as to span each of the divided core The noise suppression circuit described in 1. A circuit for suppressing common mode noise propagating in the same phase through the first and second conductive lines,
First and second windings inserted in series with each other in the first conductive line;
The first winding includes a third winding and a first capacitor connected in series, one end connected between the first winding and the second winding, and the other end grounded. A series circuit;
Fourth and fifth windings inserted in series with each other in the second conductive line;
The second winding includes a sixth winding and a second capacitor connected in series, one end connected between the fourth winding and the fifth winding, and the other end grounded. A series circuit;
The first and second windings, and the common core around which the third winding, the fourth and fifth windings, and the sixth winding are wound. Noise suppression circuit. When the coupling coefficient between the first winding and the third winding is k2, and the coupling coefficient between the second winding and the third winding is k3,
The values of the coupling coefficients k2 and k3 are 0.5 or less, respectively, and the coupling coefficient between the fourth winding and the sixth winding is k5, the fifth winding and the sixth winding When the coupling coefficient with the winding of k is k6,
The noise suppression circuit according to claim 7, wherein the values of the coupling coefficients k5 and k6 are each 0.5 or less. The coupling coefficients k2 and k3 have the same value, and
The noise suppression circuit according to claim 8, wherein the coupling coefficients k5 and k6 have the same value. The self-inductance of the third winding is L3,
The mutual inductance between the first winding and the second winding is M1, the mutual inductance between the first winding and the third winding is M2, and the second winding. And the mutual inductance between the third winding and the third winding is M3,
L3 ≧ M1 + M2-M3
Satisfy the conditions of
And the self-inductance of the sixth winding is L6,
The mutual inductance between the fourth winding and the fifth winding is M4, the mutual inductance between the fourth winding and the sixth winding is M5, and the fifth winding. When the mutual inductance between the coil and the sixth winding is M6, the following condition is satisfied: L6 ≧ M4 + M5-M6
The noise suppression circuit according to any one of claims 7 to 9, wherein In the core, the third winding is wound at a position different from the first and second windings, and magnetic flux generated by the third winding at each winding position is the first and second windings. 2 is wound in the opposite direction to the magnetic flux generated by the windings of 2,
The sixth winding is wound at a position different from the fourth and fifth windings, and the magnetic flux generated by the sixth winding at each winding position is the fourth and fifth windings. The noise suppression circuit according to any one of claims 7 to 10, wherein the noise suppression circuit is wound in a direction opposite to a magnetic flux generated by the winding. The core is composed of a plurality of divided cores,
It said first and second windings, and the third winding and the fourth and fifth windings, as well as the winding of the sixth, and extended over to each of the divided core noise suppression circuit according to any one of claims 7 to 11, characterized in that he wound. One end of the first capacitor of the first series circuit is connected between the first winding and the second winding, and one end of the second capacitor of the second series circuit is Connected between the fourth winding and the fifth winding;
In addition, the third winding of the first series circuit and the sixth winding of the second series circuit are shared, and one end of the shared winding is connected to the first and second windings. Connected to the other end of each capacitor of the second series circuit, the other end is grounded,
The common winding is wound around the common core together with the first and second windings and the fourth and fifth windings. Noise suppression circuit.

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