Noise Filter

Abstract

A noise filter (1) comprises a first capacitor (16) and a second capacitor (17) as two line capacitors, wherein the currents flowing through the first capacitor (16) and the second capacitor (17) are made to be opposite to each other, and the currents flowing through the first connecting wiring (12) and the second connecting wiring (15) are made to be parallel and in the same direction, so that the connecting wiring and the line capacitors are magnetically coupled, and the residual inductance of the line capacitors themselves is reduced to further improve the attenuation characteristics for normal mode noise.

Description

Technical Field

[0001] The present invention relates to a noise filter connected between an AC power supply and a converter circuit, between a battery and an inverter circuit, or the like, for example. Background Art

[0002] The noise filter has the function of reducing the high-frequency noise caused by the control circuit and switch circuit of various electrical devices connected to the noise filter. The high-frequency noise can be decomposed into normal mode noise and common mode noise. Normal mode noise is the noise that propagates from the noise source to the load via the signal line. On the other hand, common mode noise is the noise that propagates to the ground side via the signal line. However, the ground side does not necessarily have to be the ground, but also includes the metal frame.

[0003] As one method of reducing normal mode noise, a noise filter has been disclosed in which wirings between capacitors are crossed an odd number of times so that currents in two inter-line capacitors flow in opposite directions (see, for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6113292 (pp. 4-5, Figure 1 , 2 ) Summary of the invention

[0007] In the conventional noise filter, the currents of the two line capacitors are in opposite directions, so the magnetic coupling between the two line capacitors can be reduced. As a result, the attenuation characteristics for normal mode noise can be improved.

[0008] However, the residual inductance of the line capacitor itself cannot be reduced, so the attenuation characteristics for normal mode noise cannot be significantly improved.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the residual inductance of the line capacitor itself to further improve the attenuation characteristics with respect to normal mode noise.

[0010] The noise filter involved in the present invention comprises: a first lead-in wiring, one end of which becomes the first lead-in end; a second lead-in wiring, one end of which becomes the second lead-in end; a third lead-in wiring, one end of which becomes the third lead-in end; a fourth lead-in wiring, one end of which becomes the fourth lead-in end; a first connecting wiring, connecting the other end of the first lead-in wiring and the other end of the fourth lead-in wiring; a second connecting wiring, connecting the other end of the second lead-in wiring and the other end of the third lead-in wiring; a first capacitor connected between the first lead-in wiring and the second lead-in wiring; and a second capacitor connected between the third lead-in wiring and the fourth lead-in wiring, wherein at least a portion of the first connecting wiring and the second connecting wiring are parallel.

[0011] In the present invention, the currents flowing through the first capacitor and the second capacitor as two line capacitors are made to flow in opposite directions, and the currents flowing through the first connection wiring and the second connection wiring are made to flow in parallel and in the same direction, so that the connection wiring and the line capacitors can be magnetically coupled. As a result, the residual inductance of the line capacitor itself can be reduced, and the attenuation characteristics for normal mode noise can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of a noise filter in Embodiment 1 of the present invention.

[0013] Figure 2 It is a schematic diagram of a noise filter in Embodiment 1 of the present invention.

[0014] Figure 3 It is an explanatory diagram of the noise filter in the first embodiment of the present invention.

[0015] Figure 4 It is an explanatory diagram of the noise filter in the first embodiment of the present invention.

[0016] Figure 5 It is an explanatory diagram of the noise filter in the first embodiment of the present invention.

[0017] Figure 6 It is an explanatory diagram of the noise filter in the first embodiment of the present invention.

[0018] Figure 7 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0019] Figure 8 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0020] Fig. 9 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0021] Fig.10 It is a characteristic diagram of the noise filter according to the first embodiment of the present invention.

[0022] Fig.11 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0023] Fig.12 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0024] Fig.13 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0025] Fig.14 It is a schematic diagram of the noise filter according to the first embodiment of the present invention.

[0026] Fig.15 It is a schematic diagram of a converter device according to Embodiment 2 of the present invention.

[0027] Fig.16 It is a schematic diagram of a noise filter in accordance with Embodiment 3 of the present invention.

[0028] Fig.17 It is a schematic diagram of a noise filter in accordance with Embodiment 3 of the present invention.

[0029] Fig.18 It is a schematic diagram of a noise filter in accordance with a fourth embodiment of the present invention.

[0030] Fig.19 It is a schematic diagram of a noise filter in accordance with the fifth embodiment of the present invention.

[0031] Fig. 20 It is a schematic diagram of a noise filter in accordance with the fifth embodiment of the present invention.

[0032] Fig.21 It is a schematic diagram of a noise filter in accordance with Embodiment 6 of the present invention.

[0033] Fig. 22 It is a schematic diagram of a noise filter in accordance with Embodiment 6 of the present invention.

[0034] Fig.23 It is a schematic diagram of a noise filter in accordance with Embodiment 7 of the present invention.

[0035] Fig.24 It is a schematic diagram of a noise filter in accordance with Embodiment 8 of the present invention.

[0036] Fig.25 It is a schematic diagram of a noise filter in accordance with Embodiment 8 of the present invention.

[0037] Fig.26 It is a schematic diagram of a noise filter in Embodiment 9 of the present invention.

[0038] Fig. 27 It is a schematic diagram of a noise filter in Embodiment 9 of the present invention.

[0039] Fig.28 It is a schematic diagram of a noise filter in accordance with a tenth embodiment of the present invention.

[0040] Fig.29 It is a schematic diagram of a noise filter in accordance with Embodiment 11 of the present invention.

[0041] Fig.30 This is a schematic diagram of a noise filter in accordance with Embodiment 12 of the present invention.

[0042] (Explanation of Reference Numerals)

[0043] 1: Noise filter; 2: First lead-in end; 3: First lead-in wiring; 4: Second lead-in end; 5: Second lead-in wiring; 6: Third lead-in end; 7: Third lead-in wiring; 8: Fourth lead-in end; 9: Fourth lead-in wiring; 10, 11, 13, 14: Ends, 12: First connection wiring; 15: Second connection wiring; 16: First capacitor; 17: Second capacitor; 21: First layer; 22: Second layer; 23, 24: Through hole; 25: Converter; 26: AC power supply; 41: Commercial power supply (AC power supply); 42: Outdoor unit; 43: Converter circuit; 44: Motor; 45: Inverter circuit; 48, 50: Ground wire; 51: Printed circuit board; 52: Wiring section; 53: Jumper; 55: Electromagnetic shielding section; 47, 56: Ground; 57: Third layer; 58: Conductor layer; 59: Clearance area. DETAILED DESCRIPTION

[0044] Implementation method 1.

[0045] Figure 1 It is a schematic diagram of a noise filter according to Embodiment 1 for implementing the present invention. Figure 1 This is a perspective view schematically showing a wiring pattern of a noise filter using a two-layer printed circuit board. The noise filter 1 of this embodiment includes:

[0046] The first lead-in wiring 3 has one end portion serving as the first lead-in end portion 2;

[0047] The second lead-in wiring 5 has one end portion serving as a second lead-in end portion 4;

[0048] The third lead-in wiring 7 has one end portion serving as a third lead-in end portion 6;

[0049] The fourth lead-in wiring 9 has one end portion serving as a fourth lead-in end portion 8;

[0050] A first connection wiring 12 connects the other end 10 of the first lead-in wiring 3 and the other end 11 of the fourth lead-in wiring 9;

[0051] The second connection wiring 15 connects the other end 13 of the second lead-in wiring 5 and the other end 14 of the third lead-in wiring 7;

[0052] A first capacitor 16 connected between the first lead-in wiring 3 and the second lead-in wiring 5; and

[0053] The second capacitor 17 is connected between the third lead-in wiring 7 and the fourth lead-in wiring 9 .

[0054] The printed circuit board of this embodiment is a two-layer printed circuit board, and the end portions and wirings other than the second connecting wiring 15 are formed on the first layer 21, and the second connecting wiring 15 is formed on the second layer 22. The first layer 21 and the second layer 22 are arranged with an insulating layer (not shown) interposed therebetween.

[0055] The other end 13 of the second lead-in wiring 5 and the second connection wiring 15, and the other end 14 of the third lead-in wiring 7 and the second connection wiring 15 are connected via through holes 23 and 24. The first connection wiring 12 and the second connection wiring 15 are arranged in parallel vertically with an insulating layer interposed therebetween.

[0056] In the present embodiment, for example, a converter 25 including a switching circuit is connected between the first introduction end 2 and the second introduction end 4 of the noise filter 1, and for example, an AC power supply 26 is connected between the third introduction end 6 and the fourth introduction end 8.

[0057] In addition, Figure 1 In the diagram, the direction perpendicularly penetrating the conductor layer and the insulating layer of the printed circuit board is defined as the z-axis, the direction parallel to the first connection wiring 12 and the second connection wiring 15 is defined as the y-axis, and the direction perpendicular to the z-axis and the y-axis is defined as the x-axis.

[0058] Figure 2 Schematic diagram showing the circuit structure of the noise filter 1 in this embodiment. Figure 2 In Figure 1 The signs of are the same. In addition, the xyz axis is also the same. Figure 2 In FIG. 1 , arrows indicated on the first connection wiring 12 and the second connection wiring 15 indicate that the first connection wiring 12 and the second connection wiring 15 are parallel. Figure 2, explaining the operation of the noise filter of this embodiment. In addition, in the following description, current means alternating current, and from the perspective of the noise filter, it refers to the noise current generated by the control signal of the device and the high-frequency signal that is not needed in the power supply. This noise current is generated due to the rapid time change of the voltage and current generated during switching, and the resonance phenomenon. Regarding the conduction noise transmitted by the high-frequency signal passing through the conductor, for example, in the International Electrical Standards Conference (IEC), a predetermined value is determined in the range of 150kHz to 30MHz. In addition, regarding the radiation noise generated by releasing the high-frequency signal from the conductor to the space, the predetermined value is determined in the range of 30MHz to 1GHz in the IEC. In addition, such a high-frequency signal becomes the cause of malfunction of the device and destruction of the electronic circuit inside the device, so it is best not to exist. In vehicle equipment, etc., strict predetermined values ​​are sometimes determined in a wider frequency band. In order to reduce its noise, a noise filter such as this embodiment is used.

[0059] Figure 3 1 is an explanatory diagram showing the operation of the noise filter 1 in this embodiment. Figure 3 In FIG. 1 , the arrow indicates the direction in which the noise current flows. It is assumed that the noise current generated by the high-frequency signal flows into the noise filter 1 from the converter 25 connected between the first lead-in end 2 and the second lead-in end 4. The description is given assuming that the first lead-in end 2 is the positive pole and the second lead-in end 4 is the negative pole. The noise current flowing in from the first lead-in end 2 is divided into the noise current flowing in the first capacitor 16 and the noise current flowing in the first connection wiring 12 through the first lead-in wiring 3. Here, for simplicity, it is assumed that the current value flowing in the first capacitor 16 is equal to the current value flowing in the first connection wiring 12, but in an actual circuit, the residual inductance and residual resistance components of the first capacitor are usually larger than the residual inductance and residual resistance of the wiring, so the current value flowing in the first capacitor is generally smaller than the current value flowing in the first connection wiring.

[0060] The noise current flowing through the first capacitor 16 returns to the converter 25 via the second lead-in wiring 5 and the second lead-in end 4. The noise current flowing through the first connection wiring 12 is divided into a noise current flowing through the second capacitor 17 and a noise current flowing into the AC power supply 26 via the fourth lead-in wiring 9. Here, for simplicity, it is assumed that the current value flowing through the second capacitor 17 is greater than the current value flowing into the AC power supply 26, but in an actual circuit, since the inductance of the wiring and the impedance on the AC power supply side including the internal impedance of the AC power supply are large, the current value flowing through the second capacitor 17 is generally greater.

[0061] In addition, even when the impedance on the AC power supply side is low, a normal mode choke coil or a common mode choke coil generally used as a noise filter can be used between the AC power supplies as the noise filter of this embodiment. The reason is that in a normal mode choke coil, the impedance on the AC power supply side increases due to the influence of the inductance component and the residual resistance, and in a common mode choke coil, the impedance on the AC power supply side increases due to the influence of the inductance component and the residual resistance caused by the leakage magnetic field.

[0062] The noise current flowing through the second capacitor 17 becomes the noise current flowing through the second connection wiring 15 via the third introduction wiring 7. In this way, the noise current flowing from the converter 25 flows through the noise filter 1.

[0063] Figure 4 1 is an explanatory diagram showing the operation of the noise filter 1 in this embodiment. Figure 4 In FIG. 1 , the loop shown by the dotted line is the magnetic field around the wiring generated according to the right-hand spiral law due to the noise current flowing from the converter 25. Figure 4 In the magnetic field shown, the parts with the same direction strengthen each other, and the parts with opposite directions weaken each other. Here, it is assumed that the current value flowing through the first capacitor 16 is the same as the current value flowing through the first connection wiring 12. Therefore, in the area between the first capacitor 16 and the first connection wiring 12, the magnetic fields generated by the currents flowing therethrough are substantially the same in intensity and opposite to each other, so it can be considered that they are canceled out. Therefore, the magnetic field remaining in this area becomes the magnetic field generated by the noise current flowing through the second connection wiring 15. The area between the second capacitor, the first connection wiring, and the second connection wiring can also be considered in the same way. In this area, the magnetic fields formed by the currents flowing therethrough are in the same direction, so they do not cancel each other out but strengthen each other.

[0064] Figure 5 FIG. 1 is an explanatory diagram showing a magnetic field generated in a noise filter and an induced current generated by the induced electromotive force thereof in this embodiment. Figure 5 In the embodiment, the magnetic field generated in the region between the first capacitor 16 and the first connection wiring 12 and the second connection wiring 15 can be considered as a magnetic field that penetrates the virtual loop formed by the first capacitor 16, the second lead-in wiring 5, the first connection wiring 12, and the first lead-in wiring 3 when viewed from the z-axis direction, so an induced electromotive force is generated in accordance with Lenz's law at each portion forming the virtual loop. Similarly, the magnetic field generated in the region between the second capacitor 17 and the first connection wiring 12 and the second connection wiring 15 can be considered as a magnetic field that penetrates the virtual loop formed by the second capacitor 17, the fourth lead-in wiring 9, the first connection wiring 12, and the third lead-in wiring 7 when viewed from the z-axis direction, so an induced electromotive force is generated in accordance with Lenz's law at each portion forming the virtual loop.

[0065] Furthermore, the magnetic field formed by the magnetic field penetrating the region between the first capacitor 16, the second lead-in wiring 5, the first connection wiring 12, and the first lead-in wiring 3 in the -z direction and the magnetic field penetrating the region between the second capacitor 17, the fourth lead-in wiring 9, the first connection wiring 12, and the third lead-in wiring 7 in the +z direction includes the first connection wiring 12 and the second connection wiring 15. As a result, an induced electromotive force is generated in the first connection wiring 12 and the second connection wiring 15 according to Lenz's law. In addition, the induced electromotive force is also called the back electromotive force, but in this embodiment, it is uniformly described as the induced electromotive force.

[0066] Figure 5 The arrows shown represent the induced current generated by the induced electromotive force. With respect to the first capacitor 16, the induced current occurs in the direction from the first lead-in wiring 3 to the second lead-in wiring 5; with respect to the second capacitor 17, the induced current occurs in the direction from the third lead-in wiring 7 to the fourth lead-in wiring 9; with respect to the first connecting wiring, the induced current occurs in the direction from the fourth lead-in wiring 9 to the first lead-in wiring 3; and with respect to the second connecting wiring 15, the induced current occurs in the direction from the second lead-in wiring 5 to the third lead-in wiring 7.

[0067] In addition, in the case of considering the induced electromotive force, the above-mentioned imaginary loop is considered as a closed loop. The following shows the conditions for considering the imaginary loop as a closed loop. The phase of the current flowing in the second lead-in wiring 5 is delayed due to the length of the wiring of the fourth lead-in wiring 9, the second capacitor 17, and the third lead-in wiring 7 relative to the phase of the current flowing in the first lead-in wiring 3, the first connection wiring 12, and the first capacitor 16. However, if the electrical length caused by the length of the wiring of the fourth lead-in wiring 9, the second capacitor 17, the third lead-in wiring 7, and the second lead-in wiring 5 is less than 1 / 2 of the wavelength of the current, the delay of the phase can be ignored, and it can be considered that a closed loop is formed.

[0068] For example, consider the case of a noise filter that attenuates a noise current with a frequency of 100MHz. When the total length of the fourth lead-in wiring 9, the second capacitor 17, the third lead-in wiring 7, and the second lead-in wiring of the noise filter is set to 0.1m, since 100MHz is a wavelength of 3m, the wiring length / wavelength is 0.1m / 3m, which is less than 1 / 2, and the virtual loop can be considered as a closed loop. In addition, in the same noise filter, for a noise current of 1GHz, since 1GHz is a wavelength of 0.3m, the wiring length / wavelength is 0.1m / 0.3m, which is less than 1 / 2, and in this case, the virtual loop can also be considered as a closed loop. In addition, the wiring length / wavelength of 1 / 2 is the minimum condition, and the ratio is preferably small. Therefore, it is best to shorten the wiring length of the noise filter.

[0069] Figure 6 It shows that from Figure 3 The converter 25 shown in FIG. 1 generates noise current due to the high frequency signal in the noise filter 1, and Figure 5 The diagram is an illustration of the flow of the current synthesized by the induced current generated by the induced electromotive force shown in FIG. Figure 6 In the figure, the size of the arrow in the figure qualitatively indicates the size of the current, which means that the larger the arrow, the greater the current. Figure 6 As shown, the current flowing through the first capacitor 16 increases due to the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15. In addition, it can be seen that the current flowing through the first connection wiring 12 and the second connection wiring 15 decreases, and the current flowing through the second capacitor 17 also decreases. In other words, the residual inductance of the first capacitor 16 appears to decrease, and the current flowing through the first capacitor 16 increases. In addition, the residual inductance of the first connection wiring 12 and the second connection wiring 15 appears to increase, and the current flowing through the first connection wiring 12 and the second connection wiring 15 decreases.

[0070] The reduction in the current flowing through the second capacitor 17 is a disadvantage of a noise filter in a normal mode, but the advantage of increasing the residual inductance of the first connection wiring 12 and the second connection wiring 15 and reducing the residual inductance of the first capacitor 16 to facilitate the flow of current is greater than this disadvantage.

[0071] As described above, in the noise filter of the present embodiment, at least a portion of the first connection wiring 12 and the second connection wiring 15 are made parallel, so that the current flowing through the first capacitor 16 increases due to the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15. As a result, the residual inductance of the line capacitor itself can be reduced, and the attenuation characteristics for normal mode noise can be further improved.

[0072] Next, the effect of improving the attenuation characteristics of the noise filter according to the present embodiment with respect to normal mode noise will be described in more detail.

[0073] Figure 7 This is a schematic diagram of a conventional noise filter for comparison. Figure 7In the noise filter similar to the present embodiment, there is no first connection wiring and a second connection wiring structure. In the noise filter, the first lead-in wiring 3 and the third lead-in wiring 7 are directly connected, and the second lead-in wiring 5 and the fourth lead-in wiring 9 are directly connected. Therefore, the direction of the current flowing through the first capacitor 16 and the direction of the current flowing through the second capacitor 17 become the same direction. Therefore, the magnetic field between the two capacitors generates a magnetic field of the same intensity in the opposite direction, and the magnetic field is canceled. As a result, no induced current is generated in each capacitor, so it is impossible to improve the attenuation characteristics for normal mode noise as in the noise filter of the present embodiment.

[0074] also, Figure 7 The conventional noise filter shown can be regarded as a filter including one capacitor formed by adding the capacitances of two capacitors. In contrast, by adopting the structure of this embodiment, the residual inductance of the first connecting wiring 12 and the second connecting wiring 15 is improved, thereby functioning as a structure in which an inductor is inserted into the wiring connecting the two line capacitors. This structure becomes the same as the known π-type filter with a large noise reduction effect for the normal mode. By combining the effect of the π-type filter and the reduction of the residual inductance of the first capacitor 16, a filter with a high noise reduction effect for the normal mode is obtained.

[0075] Figure 8 This is a schematic diagram of a conventional noise filter for comparison. Figure 8 This is a noise filter having a structure in which the first connection wiring and the second connection wiring intersect with each other in the same noise filter as that in the present embodiment. Fig. 9 Observed from the z-axis direction Figure 8 Schematic diagram of a conventional noise filter shown in FIG. In this noise filter, the other end 10 of the first lead-in wiring 3 and the other end 11 of the fourth lead-in wiring 9 are connected by the first connection wiring 12, and the other end 13 of the second lead-in wiring 5 and the other end 14 of the third lead-in wiring 7 are connected by the second connection wiring 15. Therefore, the direction of the current flowing through the first capacitor 16 and the direction of the current flowing through the second capacitor 17 become opposite directions. Therefore, the magnetic coupling between the two inter-line capacitors can be reduced, so that the attenuation characteristics for normal mode noise can be generated. However, the first connection wiring and the second connection wiring cross each other, so the magnetic field around the wiring generated according to the right-hand spiral law due to the current flowing through each wiring does not weaken or strengthen each other. Therefore, the effect of reducing the residual inductance of the inter-line capacitor itself to further improve the attenuation characteristics for normal mode noise cannot be obtained.

[0076] Fig.10 is a characteristic diagram showing the measured attenuation characteristics of the noise filter according to the present embodiment. Fig.10 In the figure, the horizontal axis is the frequency, and the vertical axis is the S parameter in the mixed-mode that represents the attenuation performance for normal mode noise: Sdd21. When a positive or negative signal is input between the first lead-in end 2 and the second lead-in end 4 of the noise filter, a positive or negative signal is output between the third lead-in wiring 7 and the fourth lead-in end 8, and Sdd21 is represented by the ratio of the amplitude of the output signal to the amplitude of the input signal. Therefore, it can be said that the smaller Sdd21 is, the higher the attenuation performance of the noise filter is.

[0077] exist Fig.10 In the figure, the solid line 31 is Figure 2 The attenuation characteristics of the noise filter of this embodiment are shown in FIG. 3 , and the dashed line 32 is Figure 7 The attenuation characteristics of the conventional noise filter in the structure without the first connecting wiring and the second connecting wiring are shown in FIG. Figure 8 The attenuation characteristics of the conventional noise filter in the structure where the first connecting wiring and the second connecting wiring cross each other are shown. Fig.10 In the noise filter used in the measurement, the first capacitor and the second capacitor are polyester film capacitors model LE334 (0.33μF, size 17.5mm×17.5mm×9.5mm) manufactured by Akitani Electric Industry Co., Ltd., and the distance between the capacitors, the wiring length of each wiring, and the distance between wirings other than the first connecting wiring and the second connecting wiring are equal.

[0078] exist Fig.10 In the above equation, the frequency at which the value of Sdd21 becomes the minimum is called the resonance frequency. Fig.10 In the noise filter shown, there is a difference in attenuation performance at frequencies higher than the resonance frequency. In particular, when the noise filter of this embodiment is compared with a conventional noise filter having a structure in which the first connection wiring and the second connection wiring intersect, it can be seen that the attenuation characteristics are improved by about 8 dB in the entire range of frequencies higher than the resonance frequency.

[0079] In frequencies lower than the resonance frequency, the capacitance component of the capacitor generally determines the attenuation characteristics compared to the residual inductance of the capacitor. In contrast, in frequencies higher than the resonance frequency, the residual inductance of the capacitor determines the attenuation characteristics, and in the noise filter of this embodiment, an improvement in the attenuation characteristics for normal mode noise is observed in this frequency band. In order to improve the attenuation characteristics in the frequency band lower than the resonance frequency, a capacitor with a large capacitance component can be used. Regardless of what kind of capacitor is used, as long as it is the noise filter of this embodiment, the attenuation characteristics for normal mode noise can be improved.

[0080] In addition, in this embodiment, an example of connecting a noise filter between a converter including a switching circuit and an AC power supply to attenuate the noise generated from the converter is described, but it can also be applied to noise other than this. When giving an example here, it can also be applied to the following noises mixed into artificially produced signals: noise generated from digital devices represented by switching circuits and clock pulses; noise from high-frequency utilization equipment represented by relay circuits, thermostat discharges, commutator motors, semiconductor control equipment, etc., discharge machining machines, and heating devices; noise from power substation equipment represented by insulator discharges, and equipment related to automobiles and trams represented by ignition devices and pantograph discharges; noise from wireless equipment represented by broadcasting, wireless communication, radar, and mobile phones. In addition, it can also be applied to noises generated in nature such as lightning discharges, solar winds, astronomical radio sources, and electrostatic discharges.

[0081] In this embodiment, a noise filter is connected between the converter and the AC power supply, but a DC power supply or the like may be used instead of the AC power supply. In addition, any structure may be connected as long as it is not a circuit that generates a high-frequency signal such as a switching element. However, since it is a noise filter with high symmetry, it does not lose its effect as a noise filter even if it is between circuits that output high-frequency signals.

[0082] In the noise filter of this embodiment, the thickness direction of the printed circuit board with respect to the two layers is Figure 1 In the z-axis direction shown in FIG. 1 , the first connection wiring and the second connection wiring are arranged in parallel. Therefore, there is no need to increase the distance between the converter 25 connected to the noise filter and the AC power supply 26. Figure 1 The x-axis dimension of the noise filter is shown.

[0083] Fig.11 Schematic diagram showing the circuit structure of another noise filter in this embodiment. Figure 1 as well as Figure 2 In the noise filter shown in FIG. 1 , the first connecting wiring 12 and the second connecting wiring 15 are both in a straight line shape and are arranged parallel to each other in the z-axis direction. Fig.11 In the other noise filter shown, the first connecting wiring 12 and the second connecting wiring 15 are bent, but are parallel to each other in the z-axis direction in the bent state.

[0084] In the noise filter thus configured, the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15 increases the current flowing through the first capacitor 16. As a result, the residual inductance of the line capacitor itself can be reduced, further improving the attenuation characteristics for normal mode noise.

[0085] Fig.12 Schematic diagram showing the circuit structure of another noise filter in this embodiment. Figure 1 as well as Figure 2 In the noise filter shown in FIG. 1 , the first connecting wiring 12 and the second connecting wiring 15 are both in a straight line shape and are arranged parallel to each other in the z-axis direction. Fig.12 In the other noise filter shown, the first connecting wiring 12 and the second connecting wiring 15 are both in a straight line and parallel to each other, but are arranged offset in the x-axis direction. Fig.13 Observed from the z-axis direction Fig.12 The schematic diagram of the noise filter is shown in Figure 1. Fig.13 As shown in FIG. 1 , the first connection wiring 12 and the second connection wiring 15 of the noise filter are both in a straight line and offset in the x-axis direction, but are arranged in parallel in the y-axis direction.

[0086] In the noise filter thus configured, the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15 increases the current flowing through the first capacitor 16. As a result, the residual inductance of the line capacitor itself can be reduced, further improving the attenuation characteristics for normal mode noise.

[0087] In addition, in the present embodiment, the first connection wiring 12 and the second connection wiring 15 are arranged in parallel, but they do not need to be completely parallel. As long as the induced electromotive force caused by the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15 increases the induced current flowing through the first capacitor 16, as long as such an effect is achieved, deviation from complete parallelism may occur.

[0088] As the first capacitor and the second capacitor, various capacitors such as a laminated ceramic capacitor, a film capacitor, and an electrolytic capacitor can be used. If a noise filter is constructed as described in this embodiment, the attenuation characteristics for normal mode noise can be improved regardless of the type of capacitor. The reason is that by generating an induced electromotive force, it is easy for current to flow through the first capacitor, and it is difficult for current to flow through the first connection wiring and the second connection wiring, thereby achieving a structure that improves the effect of the noise filter.

[0089] In addition, in order to suppress pulsation, two smoothing capacitors are often used between switch circuits such as between a converter circuit and an inverter circuit. By adopting the structure described in this embodiment for the two smoothing capacitors, the inductance of the smoothing capacitor with large residual inductance can also be reduced, so the smoothing capacitor can also function as a noise filter. As a result, additional parts for noise filters and their installation space are not required. In addition, the noise generated in one circuit can be prevented from being mixed into the other circuit, so the stable operation of the converter circuit and the inverter circuit can be achieved.

[0090] Fig.14 Schematic diagram showing the circuit structure of another noise filter in this embodiment. Fig.14 As shown, the first capacitor 16 is formed by two capacitors connected in parallel. The first capacitor and the second capacitor may be formed by a combination of capacitors connected in series and in parallel.

[0091] In addition, in this embodiment, the noise filter using the printed circuit board is described, but it can also be composed of conductor bars such as bus bars, lead wires, etc. without using the printed circuit board. In addition, the noise filter can also be composed of a combination of a printed circuit board and lead wires.

[0092] Implementation method 2.

[0093] In the noise filter described in Embodiment 1, as Figure 2 It can be seen that the group of the first introduction end and the second introduction end and the group of the third introduction end and the fourth introduction end are equivalent to each other. That is, one group is the input end, and the other group is the output end. In the first embodiment, it is described that the noise current flows in from the first introduction end, but in the second embodiment, an example is described in which the noise current flows in from the third introduction end.

[0094] Fig.15 This is a schematic diagram of the case where the outdoor unit of the air conditioner is provided between the power supply and the outdoor unit of the air conditioner in this embodiment. Fig.15 In the embodiment, a commercial power source (AC power source) 41 is connected between the first introduction end 2 and the second introduction end 4 of the noise filter 1, and an outdoor unit 42 is connected between the third introduction end 6 and the fourth introduction end 8. The outdoor unit 42 includes: a converter circuit 43 that converts the AC power supplied from the commercial power source 41 via the noise filter 1 into DC power; and an inverter circuit 45 that supplies three-phase drive power for controlling the motor 44 based on the DC power output from the converter circuit 43. The converter circuit 43 and the inverter circuit 45 include switching elements. The structure of the noise filter is the same as that of the first embodiment.

[0095] In this embodiment, the noise current caused by the switching circuit flows into the noise filter from the outdoor unit 42 side having the switching element. In the noise filter of this embodiment, at least a part of the first connection wiring and the second connection wiring is made parallel, so the current flowing in the second capacitor increases due to the magnetic field formed by the noise current flowing through the first connection wiring and the second connection wiring. As a result, the residual inductance of the line capacitor itself can be reduced to further improve the attenuation characteristics for normal mode noise.

[0096] In addition, in the present embodiment, the converter circuit 43 is shown as an example of an interleaved boost converter, but any converter circuit may be used. As for the inverter circuit, converter circuit, etc., it is mainstream to use semiconductors made of silicon as a raw material to form them, but in recent years, wide bandgap semiconductors made of silicon carbide, gallium nitride, gallium oxide, diamond, etc. are used, which have higher power conversion efficiency, are small and operate at high speed. Since these wide bandgap semiconductors can operate at high speed, they have shorter rise time and fall time than conventional semiconductors made of silicon as a raw material, and can reduce switching losses, but they generate higher frequency signals, so they generate noise currents with large amplitudes. Even for noise currents with large amplitudes, by using the noise filter of the present embodiment, the size and cost of the filter will not be increased in the converter circuit using wide bandgap semiconductors, and the attenuation characteristics for normal mode noise can be further improved.

[0097] Implementation method 3.

[0098] Fig.16 It is a schematic diagram of a noise filter according to Embodiment 3 for implementing the present invention. Fig.16 1 is a perspective view schematically showing a wiring pattern of a noise filter using a single-layer printed circuit board 51. The noise filter 1 of the present embodiment includes: a first lead-in wiring 3, one end of which becomes a first lead-in end 2; a second lead-in wiring 5, one end of which becomes a second lead-in end 4; a third lead-in wiring 7, one end of which becomes a third lead-in end 6; a fourth lead-in wiring 9, one end of which becomes a fourth lead-in end 8; a first connection wiring 12 connecting the other end 10 of the first lead-in wiring 3 and the other end 11 of the fourth lead-in wiring 9; a second connection wiring 15 connecting the other end 13 of the second lead-in wiring 5 and the other end 14 of the third lead-in wiring 7; a first capacitor 16 connected between the first lead-in wiring 3 and the second lead-in wiring 5; and a second capacitor 17 connected between the third lead-in wiring 7 and the fourth lead-in wiring 9.

[0099] In the noise filter of the present embodiment, the second connection wiring 15 includes a wiring portion 52 formed on the surface of a printed circuit board 51, and a jumper 53 connecting the wiring portion 52 and the other end 13 of the second lead-in wiring 5. The wiring portion 52 is formed in parallel with the first connection wiring 12, and the jumper 53 is formed so as to straddle the first connection wiring 12.

[0100] Furthermore, a converter 25 is connected between the first introduction end portion 2 and the second introduction end portion 4 of the noise filter 1 , and an AC power source 26 is connected between the third introduction end portion 6 and the fourth introduction end portion 8 .

[0101] In the noise filter thus configured, the noise current flowing from the converter 25 flows in the same direction as in Embodiment 1, flowing in the first connection wiring 12 and the second connection wiring 15. In addition, the wiring portions 52 of the first connection wiring 12 and the second connection wiring 15 are parallel.

[0102] As described above, in the noise filter of the present embodiment, at least a portion of the first connection wiring 12 and the second connection wiring 15 are made parallel, so that the current flowing through the first capacitor 16 increases due to the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15. As a result, the residual inductance of the line capacitor itself can be reduced, and the attenuation characteristics for normal mode noise can be further improved.

[0103] In addition, Fig.16 In the noise filter shown, the second connecting wiring 15 includes a wiring portion formed on the surface of the printed circuit board and a jumper crossing the first connecting wiring 12, but the first connecting wiring 12 may also include a wiring portion formed on the surface of the printed circuit board and a jumper crossing the second connecting wiring 15.

[0104] Fig.17 Schematic diagram of another noise filter involved in this embodiment. Fig.16 In the noise filter shown in FIG. 1 , the second connection wiring 15 includes a wiring portion 52 formed in parallel with the first connection wiring 12 and a jumper 53 crossing the first connection wiring 12. Fig.17 In the noise filter shown, the second connection wiring 15 includes a wiring portion 52 formed in parallel with the first connection wiring 12 and a jumper 53 that jumps over the fourth lead-in wiring 9 .

[0105] In the noise filter thus configured, the noise current flowing from the converter 25 also flows in the same direction as in Embodiment 1, the noise current flowing in the first connection wiring 12 and the noise current flowing in the second connection wiring 15. In addition, the wiring portions 52 of the first connection wiring 12 and the second connection wiring 15 are parallel.

[0106] Therefore, with Fig.16 Similarly, the noise filter shown can reduce the residual inductance of the line capacitor itself and further improve the attenuation characteristics for normal mode noise.

[0107] In addition, Fig.17 In the noise filter shown, the second connecting wiring 15 includes a wiring portion formed on the surface of the printed circuit board and a jumper across the fourth lead-in wiring 9, but the first connecting wiring 12 may also include a wiring portion formed on the surface of the printed circuit board and a jumper across the second lead-in wiring 5.

[0108] The noise filter described in this embodiment can be formed by a single-layer printed circuit board. In Embodiment 1, a noise filter formed by a two-layer printed circuit board is described, but the distance between the first connection wiring 12 and the second connection wiring 15 is determined by the thickness of the insulating layer of the printed circuit board. The thickness of the insulating layer of a multi-layer printed circuit board cannot be freely determined.

[0109] In order to increase the current flowing through the first capacitor 16 by the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15, the interval between the first connection wiring 12 and the second connection wiring 15 is preferably as short as possible. In this embodiment, the first connection wiring 12 and the second connection wiring 15 are formed in parallel on the same printed substrate, so the interval between the wirings can be shortened within the range that satisfies the insulation. As a result, the intensity of the magnetic field can be easily adjusted.

[0110] Implementation method 4.

[0111] Fig.18 : is a schematic diagram showing a circuit structure of a noise filter according to Embodiment 4 for implementing the present invention. The structure of the noise filter of this embodiment is the same as that of Embodiment 1, but is different in that a line segment connecting a connection point of the first capacitor 16 with the first lead-in wiring 3 and a connection point of the first capacitor 16 with the second lead-in wiring 5 is parallel to the y-axis direction, so that the first connection wiring 12 and the second connection wiring 15 are parallel to the y-axis direction and the direction of the current flowing in the first capacitor 16 is parallel to them.

[0112] With this configuration, it is possible to further increase the current flowing through the first capacitor 16 due to the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15 .

[0113] In addition, the direction of the current flowing through the second capacitor 17 is preferably not parallel to the first connection wiring 12 and the second connection wiring 15. For this reason, in the present embodiment, the line segment connecting the connection point of the second capacitor 17 with the third lead-in wiring 7 and the connection point of the second capacitor 17 with the fourth lead-in wiring 9 is not parallel to the y-axis direction.

[0114] With this structure, the magnetic field formed by the current flowing through the second capacitor 17 and the magnetic field formed by the current flowing through the first connection wiring 12 and the second connection wiring 15 are offset, making it difficult for the magnetic fields to reinforce each other, so the current flowing through the second capacitor 17 can be suppressed from decreasing.

[0115] Implementation method 5.

[0116] Fig.19 It is a schematic diagram of a noise filter according to Embodiment 5 for implementing the present invention. Fig.19 This is a perspective view schematically showing a wiring pattern of a noise filter using a two-layer printed circuit board. The noise filter 1 of this embodiment is the same as the noise filter of the first embodiment, but the thickness of the wiring is different.

[0117] like Fig.19 As shown, in the noise filter of the present embodiment, the wiring width of the second connecting wiring 15 is made wider than the wiring width of the first connecting wiring 12, and two through holes 23 and 24 are provided.

[0118] Fig. 20 1 is a schematic diagram showing a circuit configuration of the noise filter 1 in the present embodiment. Fig. 20 It is shown that the wiring width of the wiring portion connecting the other end 13 of the second lead-in wiring 5 and the other end 14 of the third lead-in wiring 7 is increased.

[0119] In order to avoid contact with the first connection wiring 12, the second connection wiring 15 is structured to pass through the second layer 22 of the two-layer printed circuit board. Therefore, the wiring length of the second connection wiring 15 connecting the end 13 and the end 14 is longer than the wiring length of the first connection wiring 12 connecting the end 10 and the end 11. The difference in wiring length becomes the difference in residual inductance of the wiring, so if the wiring width is the same, the residual inductance of the second connection wiring 15 is larger than the residual inductance of the first connection wiring 12. As a result, the induced electromotive force caused by the noise current flowing in the second connection wiring 15 becomes smaller.

[0120] As described in this embodiment, the wiring width of the second connection wiring 15 is made larger than the wiring width of the first connection wiring 12, and the through holes 23 and 24 are provided in two, so that it is possible to reduce the residual inductance of the second connection wiring 15. As a result, the induced electromotive force caused by the noise current flowing through the second connection wiring 15 becomes larger, and the attenuation characteristics of the noise filter can be improved.

[0121] Implementation method 6.

[0122] Fig.21 1 is a schematic diagram showing a circuit structure of a noise filter according to Embodiment 6 for implementing the present invention. The noise filter 1 of this embodiment is the same as the noise filter of Embodiment 1, but the length of the connection wiring between the first capacitor 16 and the first lead-in wiring 3 and the length of the connection wiring between the first capacitor 16 and the second lead-in wiring 5 are shortened.

[0123] By shortening the length between both ends of the first capacitor 16 in this way, it is possible to reduce the residual inductance of the first capacitor 16. As a result, the residual inductance of the line capacitor itself becomes smaller, and the attenuation characteristics for normal mode noise can be further improved.

[0124] Fig. 22 Schematic diagram showing the circuit structure of another noise filter involved in this embodiment. Fig. 22 In the noise filter shown, the length of the connection wiring between the second capacitor 17 and the third lead-in wiring 7 and the length of the connection wiring between the second capacitor 17 and the fourth lead-in wiring 9 are shortened.

[0125] By shortening the length between the two ends of the second capacitor 17 in this way, it is possible to reduce the residual inductance of the second capacitor 17. As a result, the residual inductance of the line capacitor itself becomes smaller, and the attenuation characteristics for normal mode noise can be further improved.

[0126] Implementation method 7.

[0127] Fig.23 Schematic diagram showing a circuit configuration of a noise filter according to Embodiment 7 for implementing the present invention. The noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0128] The first capacitor is formed by connecting two capacitors 16a and 16b in series, and the connection point 46 of the two capacitors is connected to the ground 47 of the ground potential by a ground line 48. Furthermore, the second capacitor is formed by connecting two capacitors 17a and 17b in series, and the connection point 49 of the two capacitors is connected to the ground 47 of the ground potential by a ground line 50. Here, the ground 47 is a metal frame of a device on which the noise filter of this embodiment is mounted, and the ground of the metal frame is preferably at the same potential within the frame, and further, the metal frame is preferably at the same potential as the ground potential.

[0129] In the noise filter configured in this way, the attenuation characteristics for normal mode noise can be further improved by the same operation as in Embodiment 1. Furthermore, since the ground is connected to the ground by the ground line, the common mode noise propagating to the ground side via the signal line can also be reduced.

[0130] In addition, the two capacitors 16a and 16b, and the two capacitors 17a and 17b can also be regarded as capacitors to the ground for reducing common mode noise. The first lead-in end 2 is assumed to be the positive electrode and the second lead-in end 4 is the negative electrode for explanation. As described in Embodiment 1, the magnetic field formed by the first connection wiring 12 and the second connection wiring 15 makes it easy for current to flow through the capacitors 16a and 17a, but since the connection points 46 and 49 of the two capacitors are connected to the ground 47, it is not easy for current to flow through the capacitors 16b and 17b. The current flowing in from the positive electrode flows into the ground via the capacitors 16a and 17b, and the current flowing out to the negative electrode flows into the ground via the capacitors 16b and 17a. At this time, in the noise filter of this embodiment, the capacitors 16a and 17a are easy to flow current due to the induced electromotive force, and on the contrary, the capacitors 16b and 17b are not easy to flow current. Therefore, the current flowing in from the positive electrode passes through the capacitor 16a through which the current easily flows and the capacitor 17b through which the current does not easily flow, and the current flowing out to the negative electrode passes through the capacitor 16b through which the current does not easily flow and the capacitor 17a through which the current easily flows. Therefore, the current value flowing from the first lead-in wiring 3 to the fourth lead-in wiring 9 and the current value flowing from the second lead-in wiring 5 to the third lead-in wiring 7 are substantially equal, and the symmetry is improved, so that the noise converted from the normal mode to the common mode can be reduced.

[0131] In addition, in this embodiment, both the first capacitor and the second capacitor are formed by two ground capacitors, but it is not recommended to form only one of the first capacitor and the second capacitor by a ground capacitor. The reason is that the capacitor 16a is easy to flow current, and the capacitor 16b is also easy to flow current, so the symmetry of the current flowing in from the positive electrode and the current flowing out to the negative electrode is deteriorated, so the noise converted from the normal mode to the common mode increases.

[0132] In the present embodiment, the first capacitor and the second capacitor are each formed of two ground capacitors, but they may be formed of a three-terminal capacitor with small residual inductance or a longitudinal and transverse inversion type multilayer ceramic capacitor with small residual inductance instead of the two ground capacitors.

[0133] Implementation method 8.

[0134] Fig.24 Schematic diagram showing a circuit configuration of a noise filter according to Embodiment 8 for implementing the present invention. Noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0135] In the noise filter of the first embodiment, the second capacitor 17 is provided on the first layer of the two-layer printed circuit board. In the present embodiment, the second capacitor 17 is arranged at a position offset in the z-axis direction relative to the first capacitor. For example, this can be achieved by providing the second capacitor 17 on the second layer in the noise filter described in the first embodiment.

[0136] In the noise filter configured in this way, the attenuation characteristics with respect to normal mode noise can be further improved due to the same operation as that of the first embodiment.

[0137] In addition, the distance between the first capacitor 16 and the second capacitor 17 is separated, so the magnetic coupling between the capacitors is reduced, and the attenuation characteristics for normal mode noise are improved. Furthermore, in a capacitor with a large size such as a film capacitor, a large potential difference is generated between the opposing surfaces of the two capacitors by crossing compared to when the wiring is not crossed. As a result, electrical coupling occurs between the two capacitors, and the path of the electrical coupling becomes a path that does not pass through the first connecting wiring 12 and the second connecting wiring 15, so the attenuation characteristics for normal mode noise are deteriorated. This electrical coupling is sufficiently small compared to the improvement in magnetic coupling, but in the structure of this embodiment, such electrical coupling does not occur, so the attenuation characteristics for normal mode are improved.

[0138] In the present embodiment, a configuration is described in which a two-layer printed circuit board is used and the first capacitor 16 is provided on the first layer and the second capacitor 17 is provided on the second layer. However, the positional relationship may be reversed.

[0139] Fig.25 Schematic diagram showing the circuit structure of another noise filter involved in this embodiment. Fig.25 As shown, portions of the third lead-in wiring 7 and the fourth lead-in wiring 9 may be extended to positions offset in the z-axis direction.

[0140] Implementation method 9.

[0141] Fig.261 is a schematic diagram showing a circuit configuration of a noise filter according to Embodiment 9 for implementing the present invention. The noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0142] In the noise filter of the first embodiment, the first connection wiring 12 and the second connection wiring 15 are arranged in parallel. In the noise filter of this embodiment, in addition, the first lead-in wiring 3 and the second lead-in wiring 5 are arranged in parallel, and the third lead-in wiring 7 and the fourth lead-in wiring 9 are also arranged in parallel.

[0143] By such a configuration, the direction of the current flowing from the first lead-in wiring 3 to the fourth lead-in wiring 9 and the direction of the current flowing from the third lead-in wiring 7 to the second lead-in wiring 5 are symmetrical in the yz plane, so the noise component caused by the conversion from normal mode to common mode due to asymmetry can be reduced.

[0144] Fig. 27 Schematic diagram showing the circuit structure of another noise filter involved in this embodiment. Fig. 27 In the noise filter shown, for Fig.26 In the structure of the noise filter shown in the figure, both ends of the first connection wiring 12 are further extended in the y-axis direction, so that the length of the first connection wiring 12 and the length of the second connection wiring 15 are the same.

[0145] With this configuration, the residual inductance of the first connection wiring 12 and the residual inductance of the second connection wiring 15 become equal, so that the noise component generated by asymmetry and converted from a normal mode to a common mode can be further reduced.

[0146] Implementation method 10.

[0147] Fig.28 1 is a schematic diagram showing a circuit configuration of a noise filter according to Embodiment 10 for implementing the present invention. The noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0148] The electromagnetic shield 55 surrounding the first capacitor 16, the second capacitor 17, the first connection wiring 12, and the second connection wiring 15 is connected to the ground 56. The ground 56 may be a metal housing of a device equipped with the noise filter of this embodiment, or may be directly connected to the ground.

[0149] The noise filter configured in this way can prevent the external magnetic field from intruding into the virtual loop formed by the first capacitor 16, the second lead-in wiring 5, the first connection wiring 12, the second connection wiring 15, and the first lead-in wiring 3, so that an induced electromotive force can be reliably generated in the virtual loop. As a result, the residual inductance of the line capacitor itself can be reduced to more reliably improve the attenuation characteristics for normal mode noise.

[0150] Implementation method 11.

[0151] Fig.29 1 is a schematic diagram showing a circuit configuration of a noise filter according to Embodiment 11 for implementing the present invention. The noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0152] In this embodiment, the printed circuit board including three layers includes a conductor layer 58 and a gap region 59 where no conductor layer is formed in the third layer 57. The gap region 59 includes an area larger than the area of ​​the second connection wiring 15 formed in the second layer 22 at a position facing the second connection wiring 15.

[0153] When it is assumed that the conductor layer 58 of the third layer 57 is formed in the entire region of the third layer 57, the conductor layer 58 blocks the magnetic field loop formed by the current flowing through the first connection wiring and the second connection wiring. As a result, the induced electromotive force generated in the virtual loop formed by the first capacitor 16, the second lead-in wiring 5, the first connection wiring 12, the second connection wiring 15, and the first lead-in wiring 3 is weakened.

[0154] As described in this embodiment, in the case of a printed circuit board including three layers, the induced electromotive force generated in the virtual loop can be efficiently generated by providing a gap layer in the third layer with an area larger than the area of ​​the second connecting wiring 15. The structure of providing the gap layer is the same when using a printed circuit board with more than four layers.

[0155] Implementation method 12.

[0156] Fig.30 1 is a schematic diagram showing a circuit configuration of a noise filter according to Embodiment 12 for implementing the present invention. The noise filter 1 of this embodiment is similar to the noise filter of Embodiment 1, but is different in the following respects.

[0157] like Fig.30As shown, in the noise filter of the present embodiment, the shapes of the other end 10 of the first lead-in wiring 3 and the other end 14 of the third lead-in wiring 7 arranged opposite to each other are rounded, and further the shapes of the other end 13 of the second lead-in wiring 5 and the other end 11 of the fourth lead-in wiring 9 arranged opposite to each other are rounded.

[0158] In the noise filter of this embodiment, the first connecting wiring 12 and the second connecting wiring 15 are arranged in parallel. Figure 8 In the conventional noise filter having a structure in which the first connection wiring and the second connection wiring are orthogonal to each other as shown, the distance between the end 10 and the end 14, and the distance between the end 13 and the end 11 are shorter. In addition, a high voltage input from the third introduction end 6 and the fourth introduction end 8 of the AC power supply 26 is applied between the first introduction wiring 3 and the third introduction wiring 7, and between the first introduction wiring 3 and the second introduction wiring 5. A potential difference is generated between the wirings, so when the distance between the ends of the wirings becomes shorter than before, discharge may occur, insulation breakdown, etc. may occur.

[0159] Discharge often occurs starting from a sharp corner. However, by rounding the shapes of the ends of wirings where a potential difference is likely to occur as described in this embodiment, it is possible to prevent discharge, insulation breakdown, and the like.

[0160] Alternatively, instead of rounding the shapes of the ends of the wiring lines that are likely to generate a potential difference, the distance between the ends of the wiring lines that are likely to generate a potential difference may be lengthened.

Claims

1. A noise filter, characterized in that: have: The first lead-in wiring has one end portion serving as a first lead-in end portion; The second lead-in wiring has one end portion serving as a second lead-in end portion; The third lead-in wiring has one end portion serving as a third lead-in end portion; The fourth lead-in wiring, one end of which becomes the fourth lead-in end; a first connection wiring connecting the other end of the first lead-in wiring and the other end of the fourth lead-in wiring; a second connection wiring connecting the other end of the second lead-in wiring and the other end of the third lead-in wiring; a first capacitor connected between the first lead-in wiring and the second lead-in wiring; as well as a second capacitor connected between the third lead-in wiring and the fourth lead-in wiring, in, The first connecting wiring and the second connecting wiring each have a linear main portion. The linear main portions of the first connection wiring and the second connection wiring are parallel to each other in a direction connecting the terminals of the first capacitor, and currents flowing in the linear main portions of the first connection wiring and the second connection wiring are in the same direction.

2. The noise filter according to claim 1, characterized in that The wiring width of the second connecting wiring is greater than or equal to the wiring width of the first connecting wiring.

3. The noise filter according to claim 1 or 2, characterized in that: The first capacitor and the second capacitor are each formed by connecting two capacitors in series, and midpoints of the two capacitors are connected to the ground.

4. The noise filter according to claim 1 or 2, characterized in that: have: The electromagnetic shielding portion surrounds the first capacitor, the second capacitor, the first connection wiring, and the second connection wiring.

5. A noise filter, characterized in that: have: The first lead-in wiring has one end portion serving as a first lead-in end portion; The second lead-in wiring has one end portion serving as a second lead-in end portion; The third lead-in wiring has one end portion serving as a third lead-in end portion; The fourth lead-in wiring, one end of which becomes the fourth lead-in end; a first connection wiring connecting the other end of the first lead-in wiring and the other end of the fourth lead-in wiring; a second connection wiring connecting the other end of the second lead-in wiring and the other end of the third lead-in wiring; a first capacitor connected between the first lead-in wiring and the second lead-in wiring; as well as a second capacitor connected between the third lead-in wiring and the fourth lead-in wiring, in, The first connection wiring and the second connection wiring each have a straight main portion, the straight main portions of the first connection wiring and the second connection wiring are parallel to each other in the same direction as the direction of the current flowing through the first capacitor, and the currents flowing through the straight main portions of the first connection wiring and the second connection wiring are in the same direction, In a printed circuit board having a two-layer structure including a first layer and a second layer provided with an insulating layer interposed therebetween, The first lead-in wiring, the second lead-in wiring, the third lead-in wiring, the fourth lead-in wiring, the first capacitor, the second capacitor, and the first connection wiring are arranged in the first layer, The second connection wiring is arranged on the second layer, The second connection wiring is connected to the other end of the second lead-in wiring and the other end of the third lead-in wiring by means of through holes provided in the insulating layer.

6. The noise filter according to claim 5, characterized in that The wiring width of the second connecting wiring is greater than or equal to the wiring width of the first connecting wiring.

7. The noise filter according to claim 5 or 6, characterized in that: The first capacitor and the second capacitor are each formed by connecting two capacitors in series, and midpoints of the two capacitors are connected to the ground.

8. The noise filter according to claim 5 or 6, characterized in that: have: The electromagnetic shielding portion surrounds the first capacitor, the second capacitor, the first connection wiring, and the second connection wiring.

9. A noise filter, characterized in that: have: The first lead-in wiring has one end portion serving as a first lead-in end portion; The second lead-in wiring has one end portion serving as a second lead-in end portion; The third lead-in wiring has one end portion serving as a third lead-in end portion; The fourth lead-in wiring, one end of which becomes the fourth lead-in end; a first connection wiring connecting the other end of the first lead-in wiring and the other end of the fourth lead-in wiring; a second connection wiring connecting the other end of the second lead-in wiring and the other end of the third lead-in wiring; a first capacitor connected between the first lead-in wiring and the second lead-in wiring; as well as a second capacitor connected between the third lead-in wiring and the fourth lead-in wiring, in, The first connection wiring and the second connection wiring each have a straight main portion, the straight main portions of the first connection wiring and the second connection wiring are parallel to each other in the same direction as the direction of the current flowing through the first capacitor, and the currents flowing through the straight main portions of the first connection wiring and the second connection wiring are in the same direction, In a 1-layer printed circuit board, At least one of the first connection wiring and the second connection wiring includes a jumper wire that spans over a wiring portion formed on a surface of the printed circuit board.

10. The noise filter according to claim 9, characterized in that The wiring width of the second connecting wiring is greater than or equal to the wiring width of the first connecting wiring.

11. The noise filter according to claim 9 or 10, characterized in that: The first capacitor and the second capacitor are each formed by connecting two capacitors in series, and midpoints of the two capacitors are connected to the ground.

12. The noise filter according to claim 9 or 10, characterized in that: have: The electromagnetic shielding portion surrounds the first capacitor, the second capacitor, the first connection wiring, and the second connection wiring.

Images