JP2019153859A - noise filter - Google Patents

Abstract

To provide a noise filter which can suppress noise of a high-frequency band over 1 GHz.SOLUTION: A noise filter 10 is a member for suppressing noise radiated from a cable 70. One end of the cable 70 is connected to a power supply device 50 encased in a housing 60, and the other end of the cable 70 is located outside the housing 60. The noise filter 10 comprises: a shielding member 20 including a conductor; and a core member 30 including a composite magnetic material 32. The shielding member 20 surrounds the cable 70. The core member 30 surrounds the cable 70 and is adjacent to the shielding member 20. The composite magnetic material 32 contains a binder 322, and soft magnetic powder 324 dispersed in the binder 322. The imaginary component μ" of a complex magnetic permeability of the composite magnetic material 32 is 1 or more and 50 or less over a frequency band from 500 MHz to 3 GHz.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a noise filter for suppressing noise radiated from a cable.

  For example, Patent Document 1 discloses this type of noise filter.

  The noise countermeasure filter (noise filter) of Patent Document 1 suppresses noise radiated from a cable connected to a semiconductor power converter (power supply device). This noise filter is composed of a core and a shield part, and functions as a low-pass filter having a resonance frequency of 10 to 25 MHz, for example. The noise filter of Patent Literature 1 can mainly suppress noise having a frequency of 100 MHz or less.

Japanese Patent No. 6137602

  As the switching element used in the power supply device increases in speed, the frequency of noise radiated from the cable connected to the power supply device increases. For example, noise in a frequency band exceeding 1 GHz may be radiated from the cable and may affect peripheral electronic devices. On the other hand, the conventional noise filter can hardly suppress noise in a high frequency band exceeding 1 GHz.

  Therefore, an object of the present invention is to provide a noise filter capable of suppressing noise in a high frequency band exceeding 1 GHz.

In the present invention, as the first noise filter,
A noise filter for suppressing noise emitted from the cable,
One end of the cable is connected to a power supply device housed inside the housing, and the other end of the cable is located outside the housing,
The noise filter includes a shield member made of a conductor and a core member made of a composite magnetic material,
The shield member surrounds the cable, and extends outside the housing along the cable so as to be separated from the housing;
The core member surrounds the cable and is adjacent to the shield member along the cable;
The composite magnetic body includes a binder and soft magnetic powder dispersed in the binder,
An imaginary component μ ″ of the complex magnetic permeability of the composite magnetic body provides a noise filter that is 1 or more and 50 or less over a frequency band from 500 MHz to 3 GHz.

Moreover, this invention is a 1st noise filter as a 2nd noise filter,
The housing is made of a conductor,
The shield member provides a noise filter in contact with the housing.

The present invention is the first or second noise filter as the third noise filter,
The core member provides a noise filter in contact with the shield member.

Further, the present invention is any one of the first to third noise filters as the fourth noise filter,
The shield member has a connected part and a protruding part,
The connected part is connected to the housing;
The protrusion provides a noise filter that is located outside the housing and protrudes away from the housing.

Moreover, this invention is a 4th noise filter as a 5th noise filter,
A passage hole is formed in the housing,
The connected portion is located inside the passage hole;
The core member provides a noise filter that is at least partially surrounded by the connected portion.

Moreover, this invention is a noise filter in any one of 1st to 4th as a 6th noise filter,
The core member provides a noise filter located at least partially within the housing.

Moreover, this invention is a noise filter in any one of 1st to 4th as a 7th noise filter,
The core member is located outside the casing and provides a noise filter that is further away from the casing than the shield member.

  In the noise filter of the present invention, the shield member and the core member are adjacent to each other while surrounding the cable. The shield member and the core member arranged in this manner function as a low-pass filter, and high frequency noise exceeding 1 GHz can be cut by adjusting the size of each. Specifically, the imaginary component μ ″ (equivalent resistance component) of the complex permeability of the composite magnetic body forming the core member of the noise filter according to the present invention is a high value of 1 or more and 50 or less over the frequency band from 500 MHz to 3 GHz. Therefore, it is possible to construct an RC filter that effectively suppresses high frequency noise exceeding 1 GHz.

It is a figure which shows typically the power supply device, housing | casing, load, cable, and noise filter in embodiment of this invention. The power supply device is shown by a block diagram, and the housing is shown by a cross-sectional view. It is a figure which shows the relative position of the noise filter with respect to the housing | casing and cable of FIG. The housing, cable, and noise filter are shown in cross-section. A part of the core member of the noise filter (portion surrounded by a one-dot chain line) is enlarged and schematically drawn. It is a perspective view which shows an example of the noise filter of FIG. The hidden outline of the shield member of the noise filter is drawn with a broken line. A part of the outline of the housing is drawn with a one-dot chain line. The position of the cable is drawn with a two-dot chain line. It is sectional drawing which expands and schematically shows a part of core member of the noise filter of FIG. It is a figure which shows the equivalent circuit of the cable and noise filter of FIG. It is a perspective view which shows the modification of the noise filter of FIG. The position of the cable is drawn with a broken line. A part of the outline of the housing is drawn with a one-dot chain line. It is a figure which shows another modification of the noise filter of FIG. It is a figure which shows the equivalent circuit of the cable and noise filter of FIG. It is a figure which shows typically the power supply device by the Example of this invention, a housing | casing, a load, a cable, and a noise filter. The power supply device is shown by a block diagram, and the casing shows an outline. It is a perspective view which shows typically the housing | casing of FIG. 9, a cable, and a noise filter. The outline of the core member located inside the housing is drawn with a broken line. It is a figure which shows the frequency characteristic of the magnetic permeability of the composite magnetic body which forms the core member of FIG. It is a figure which shows the result of having measured the noise radiated | emitted from a cable in the Example of FIG.

  Referring to FIG. 1, a noise filter 10 according to an embodiment of the present invention is used by being attached to a cable 70.

  One end (inner end 702) of the cable 70 is connected to an inverter device (power supply device) 50 housed in a housing 60 made of a conductor. The housing 60 is grounded. A passage hole 62 is formed in the housing 60. The passage hole 62 opens to the outside of the housing 60. The other end (outer end 706) of the cable 70 is drawn from the housing 60 through the passage hole 62, and is connected to a load 80 such as a motor located outside the housing 60. That is, the outer end 706 of the cable 70 is located outside the housing 60.

  The power supply device 50 includes a rectifier circuit 510, a DC power supply 530, a control circuit 550, a DC / DC converter 560, a drive circuit 570, and an inverter main circuit 590. The control circuit 550 has a PWM (pulse width modulation) circuit 552. The rectifier circuit 510 is connected between the AC power supply 40 located outside the housing 60 and the inverter main circuit 590. The DC power supply 530 is connected to the inverter main circuit 590 via the control circuit 550 and is connected to the inverter main circuit 590 via the DC / DC converter 560 and the drive circuit 570. The PWM circuit 552 is connected to the drive circuit 570.

  The power supply device 50 configured as described above converts the frequency of the AC power generated by the AC power supply 40 and supplies it to the load 80 via the cable 70. Each circuit (DC / DC converter 560, inverter main circuit 590, etc.) of the power supply device 50 includes a power semiconductor or a high-speed switching element using a high-speed semiconductor element such as SiC (silicon carbide) or GaN (gallium nitride). in use. When the power supply device 50 operates, the high-speed semiconductor element generates common mode noise (hereinafter simply referred to as “noise”) over a high frequency band of several hundred MHz to several GHz. The noise is radiated to the inside of the housing 60 and propagates through the cable 70 to be radiated to the outside of the housing 60. The noise filter 10 is a noise filter for suppressing high frequency band noise radiated from the cable 70.

  In the present embodiment, power supply device 50 is inverter device 50 that converts the frequency of AC power, and cable 70 is a three-phase cable that transmits three-phase AC power. That is, the cable 70 is composed of three covered conductors 74. However, the present invention is not limited to this. For example, the power supply device 50 may be a power supply device other than the inverter device. The circuit structure of the power supply device 50 is not limited to the present embodiment. Further, the number of the covered conductors 74 constituting the cable 70 is not limited to three.

  FIG. 2 shows a cross section of one of the three coated conductors 74 of the cable 70. Referring to FIG. 2, each of the coated conductive wires 74 of the cable 70 includes a conductive wire 742 made of a conductor such as copper and an insulating coating 744 made of an insulator such as resin. The insulating coating 744 covers the conductive wire 742. In other words, in each of the covered conductive wires 74 of the cable 70, the conductor forming the conductive wire 742 is covered with a dielectric such as resin. The cable 70 shown in FIG. 2 extends linearly between the housing 60 and the load 80. However, the present invention is not limited to this. For example, the cable 70 may extend so as to meander between the housing 60 and the load 80. That is, the direction in which the cable 70 extends may be a linear direction or a curved direction.

  Referring to FIGS. 1 and 2, the noise filter 10 includes a shield member 20 made of a conductor such as copper, aluminum, and conductive rubber, and a core member 30 made of a composite magnetic body 32. Each of the shield member 20 and the core member 30 is attached to the cable 70 and has a generally cylindrical shape.

  Referring to FIG. 2, the shield member 20 surrounds the cable 70 (three covered conductors 74) in an orthogonal plane orthogonal to the direction in which the cable 70 extends. The shield member 20 attached to the cable 70 functions as a capacitor together with each of the coated conductive wires 74 (conductive wire 742 and insulating coating 744) of the cable 70.

  Referring to FIG. 3, shield member 20 of the present embodiment is formed by winding a metal tape such as a copper foil or an aluminum foil around cable 70. Such a shield member 20 can be easily attached to a desired position of the cable 70 in a desired shape and size. However, the present invention is not limited to this. For example, the shield member 20 may be a molded product made of conductive rubber.

  As shown in FIG. 3, the shield member 20 of the present embodiment has a connected portion 22 and a protruding portion 26. The connected portion 22 is formed by bending an end portion of a metal tape wound around the cable 70. The connected portion 22 is in contact with the housing 60. In other words, the to-be-connected part 22 is directly connected to the housing 60, whereby the shield member 20 is grounded. The protruding portion 26 has a cylindrical shape. The protruding portion 26 is located outside the housing 60 as a whole and protrudes away from the housing 60.

  Referring to FIG. 2, the core member 30 surrounds the cable 70 (three covered conductors 74) in an orthogonal plane orthogonal to the direction in which the cable 70 extends. The core member 30 attached to the cable 70 functions as an inductor for each of the conductive wires 742 of the cable 70.

  2 and 3, the core member 30 of the present embodiment is formed by winding a sheet-like composite magnetic body 32 having a thickness of, for example, about 300 μm and capable of being bent flexibly around a cable 70. ing. Such a core member 30 can be easily attached to a desired position of the cable 70 in a desired shape and size. However, the present invention is not limited to this. For example, the core member 30 may be a molded product made of the composite magnetic body 32.

  2 and 4, the composite magnetic body 32 includes a binder 322 made of rubber, an elastomer, a resin, and the like, an Fe—Cr—Al—Si alloy dispersed in the binder 322, and an Fe—Si—Al system. And soft magnetic powder 324 made of an alloy or the like. The soft magnetic powder 324 of the present embodiment has a flat shape and is oriented parallel to the sheet surface. The flat soft magnetic powder 324 can be formed, for example, by processing a spherical soft magnetic powder into a flat shape using a ball mill. The sheet-like composite magnetic body 32 can be formed, for example, by dispersing soft magnetic powder 324 in a liquid binder 322 and forming a film by a doctor blade method.

  Referring to FIGS. 2 and 3, the core member 30 is adjacent to the shield member 20 along the cable 70. That is, in the noise filter 10, the shield member 20 and the core member 30 are adjacent to each other while surrounding the cable 70.

  Referring to FIG. 5, the shield member 20 and the core member 30 arranged as described above function as a low-pass filter (RC filter). This low-pass filter can cut high-frequency noise exceeding 1 GHz by adjusting the sizes of the shield member 20 and the core member 30. In other words, the cutoff frequency of the noise filter 10 (low-pass filter) can be set to a value exceeding 1 GHz. Specifically, in this low-pass filter, by adjusting the volume of the core member 30, the equivalent resistance component due to the imaginary component μ ″ of the complex permeability can be adjusted, and by adjusting the area around which the shield member 20 surrounds the cable 70, The stray capacitance can be adjusted to about several pF to several tens pF.

  Referring to FIG. 2, the conventional core member is generally made of ferrite. However, the imaginary component μ ″ (equivalent resistance component) of the complex permeability of the core member made of ferrite greatly decreases at a frequency exceeding 1 GHz. On the other hand, the core member 30 of the present embodiment is, for example, the entire composite magnetic body 32. By increasing the volume occupancy of the soft magnetic powder 324 with respect to the above, a high imaginary component μ ″ is maintained even at a frequency exceeding 1 GHz. More specifically, in the present embodiment, the imaginary component μ ″ of the complex permeability of the composite magnetic body 32 forming the core member 30 of the noise filter 10 is 1 or more over the frequency band from 500 MHz to 3 GHz. The high value of 50 or less is maintained. More desirably, the value of the imaginary component μ ″ of the complex permeability of the composite magnetic body 32 is 5 or more and 30 or less.

  That is, the noise filter 10 of the present embodiment can constitute an RC filter that effectively suppresses high frequency noise exceeding 1 GHz.

  From the viewpoint of effectively suppressing high-frequency noise, the length of the shield member 20 along the cable 70 is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 30 mm or less. Similarly, the length of the core member 30 along the cable 70 is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 30 mm or less. Moreover, it is preferable that the thickness of the core member 30 is 20 micrometers or more.

  Referring to FIG. 4, in the present embodiment, the soft magnetic powder 324 has a flat shape. By using the soft magnetic powder 324 having a flat shape, a decrease in complex permeability due to a demagnetizing field can be extremely reduced. However, the present invention is not limited to this. For example, the soft magnetic powder 324 may have a spherical shape. By using the spherical soft magnetic powder 324, a high complex permeability can be obtained at a higher frequency.

  The shield member 20 extends outside the housing 60 along the cable 70 so as to be separated from the housing 60. If part of the shield member 20 is located inside the housing 60, noise radiated into the internal space of the housing 60 may propagate through the shield member 20 and be radiated to the outside of the housing 60. There is. On the other hand, according to the present embodiment, the entire shield member 20 is located outside the housing 60, thereby preventing propagation of noise radiated into the internal space of the housing 60 to the outside of the housing 60. Has been.

  Referring to FIGS. 2 and 3, according to the present embodiment, each of the connected portion 22 and the protruding portion 26 of the shield member 20 is part of a metal tape wound around the cable 70. That is, the connected portion 22 and the protruding portion 26 of the present embodiment are formed integrally with each other. The connected portion 22 of the shield member 20 is in direct contact with the outer surface 66 of the housing 60 without passing through another conductive member (not shown) such as a ground wire. According to the present embodiment, the shield member 20 can be reliably grounded to the housing 60, and noise emission by other conductive members such as a ground wire can be prevented. That is, the shield member 20 can be grounded without increasing the noise propagation path. However, the present invention is not limited to this. For example, the shield member 20 may be somewhat away from the housing 60. In this case, the shield member 20 may be grounded to a member other than the housing 60.

  Referring to FIG. 2, the cable 70 is divided into an inner portion 710 extending inside the housing 60, a passage portion 720 positioned inside the passage hole 62, and an outer portion 730 extending outside the housing 60. it can. The outer portion 730 of the cable 70 is arranged along the direction in which the cable 70 extends, between the case side portion 732 close to the case 60, the load side portion 736 close to the load 80, and the case side portion 732 and the load side portion 736. The noise filter 10 is not attached to the intermediate part 734 and the load side part 736 of the cable 70, but is attached only to the inner part 710 and the casing side part 732.

  As described above, according to the present embodiment, noise can be suppressed only by covering only a portion of the cable 70 located in the vicinity of the housing 60 with one shield member 20 and one core member 30. The shield member 20 of the present embodiment can be formed from a commonly used metal tape. Further, as described above, the shield member 20 and the core member 30 of the present embodiment can be easily wound around the cable 70. Therefore, according to this Embodiment, the man-hour and cost for suppressing a noise can be reduced.

  According to the present embodiment, the shield member 20 of the noise filter 10 is in contact with or close to the outer surface 66 of the housing 60, and the core member 30 of the noise filter 10 is in contact with or close to the inner surface 64 of the housing 60. is doing. That is, the shield member 20 and the core member 30 are adjacent to each other across the passage hole 62 of the housing 60. However, the present invention is not limited to this, and the structure of the noise filter 10 can be variously modified as described below.

  Referring to FIG. 6, the noise filter 10 </ b> A according to the modification includes a shield member 20 </ b> A made of a conductor and a core member 30 </ b> A made of a composite magnetic body 32. The shield member 20A is formed into a cylindrical shape as a whole by molding, for example, conductive rubber. The shield member 20A includes a connected portion 22A, a mounted portion 24A, and a protruding portion 26A. The connected portion 22A and the protruding portion 26A protrude in opposite directions with the attached portion 24A interposed therebetween. A screw is formed in the connected portion 22A. The core member 30A is formed in a cylindrical shape by molding the composite magnetic body 32.

  The shield member 20 </ b> A is attached to the passage hole 62 of the housing 60. Specifically, a screw is formed on the inner wall surface of the passage hole 62 (not shown). The connected portion 22 </ b> A is screwed into the passage hole 62 and is located inside the passage hole 62. The attached portion 24 </ b> A is attached to the outer surface 66 of the housing 60. As a result, the shield member 20A is in contact with the housing 60 at the connected portion 22A and the attached portion 24A, and is thereby grounded. The core member 30A is received inside the connected portion 22A and is at least partially surrounded by the connected portion 22A. A part of the core member 30 </ b> A arranged in this way is located inside the passage hole 62, and the other part of the core member 30 </ b> A is located inside the housing 60. That is, the core member 30 is at least partially located inside the housing 60.

  The noise filter 10A configured as described above functions as a low-pass filter (RC filter) and can effectively suppress high-frequency noise exceeding 1 GHz similarly to the noise filter 10 (see FIG. 2). In particular, the shield member 20 </ b> A is located inside the passage hole 62, but does not protrude beyond the inner surface 64 of the housing 60 into the housing 60. In other words, the shield member 20 </ b> A is positioned only outside the housing 60 and inside the passage hole 62. Due to this structure, similarly to the noise filter 10, propagation of noise radiated into the internal space of the housing 60 to the outside of the housing 60 is prevented.

  When FIG. 7 is compared with FIG. 2, the noise filter 10 </ b> B according to the modification includes the same shield member 20 as the noise filter 10 and a core member 30. However, the core member 30 of the noise filter 10 </ b> B is located outside the housing 60 and is further away from the housing 60 than the shield member 20. Specifically, the core member 30 is in contact with the end of the shield member 20 on the load 80 side, and extends toward the load 80 along the direction in which the cable 70 extends.

  Referring to FIG. 8, the shield member 20 and the core member 30 arranged as described above function as a low-pass filter (CR filter). As with the noise filter 10 (see FIG. 2), the noise filter 10B can effectively suppress high-frequency noise exceeding 1 GHz.

  The noise filter according to the above-described embodiments and modifications can be further variously modified in addition to the modifications already described. For example, the core member 30 may be in contact with the shield member 20 in the noise filter 10 (see FIG. 2). In any of the noise filters described above, the shield member and the core member are separate members, but the shield member and the core member may be formed integrally with each other. Referring to FIG. 1, the noise filter 10 may be attached to a cable between the AC power supply 40 and the rectifier circuit 510.

  9 and 10, the effect of the present invention was verified using a step-down chopper power supply (power supply device) 50X. Hereinafter, a verification method and a verification result will be described.

  Referring to FIG. 9, a power supply device 50X used for verification was produced. The power supply device 50X includes a rectifier circuit 510X, a switching frequency generation circuit 540X, a drive circuit 570X, and a step-down chopper circuit 590X. The rectifier circuit 510X is connected to the AC power supply 40X, and the switching frequency generation circuit 540X is connected to the DC power supply 42X. The step-down chopper circuit 590X is equipped with a SiC element as a switching element. However, the power supply device 50X is designed so as not to radiate noise as much as possible, except for noise directly caused by switching.

  Referring to FIGS. 9 and 10, a power supply device 50X, an AC power supply 40X, and a DC power supply 42X are installed in an anechoic chamber. Specifically, a metal casing 60 is installed on the floor 88 of the anechoic chamber, and the power supply device 50X is accommodated inside the casing 60. The housing 60 was grounded to the floor surface 88. This prevents noise radiated directly from the power supply device 50X from leaking outside the housing 60. Further, a support base 86 having a height of 15 cm was installed on the floor surface 88. A cable 70 having a length of 60 cm was connected between the power supply device 50X and the load 80X. Specifically, the middle portion of the cable 70 was fixed on the support base 86, and both ends of the cable 70 were connected to the power supply device 50X and the load 80X, respectively. Thereby, the cable 70 was fixed so as to extend horizontally at a position 15 cm in height from the floor surface 88.

  A horn antenna (not shown) was fixed at a position 70 cm away from the cable 70. Specifically, the horn antenna is at the same height as the cable 70 and is separated from the cable 70 by a distance of 70 cm in a direction orthogonal to the direction in which the cable 70 extends. The frequency range of the horn antenna was 500 MHz to 6 GHz.

  Noise in the anechoic chamber and the measurement environment when the power supply device 50X was not operating was measured with a horn antenna (not shown). The measurement results are shown in the “noise floor” graph of FIG.

  The power supply device 50X was operated at a switching frequency of 100 kHz. A 200V AC current was supplied from the AC power supply 40X to the rectifier circuit 510X of the power supply device 50X, and a DC current was supplied from the DC power supply 42X to the switching frequency generation circuit 540X of the power supply device 50X. At this time, the step-down chopper circuit 590X of the power supply device 50X output a direct current of 185 V and 14.1 A. That is, an output power of about 2.6 kW was obtained.

  A horizontally polarized wave component of noise radiated from the cable 70 with the operation of the power supply device 50X was measured with a horn antenna (not shown). The measurement results are shown in the graph “before applying noise filter” in FIG.

  Next, the noise filter 10 was attached to the cable 70. Specifically, the shield member 20 is formed by winding a metal foil around a portion of the cable 70 located near the outer surface 66 of the housing 60. The metal foil of the shield member 20 was brought into contact with the housing 60 and grounded. The shield member 20 had a length of 30 mm along the cable 70 and a thickness of 35 μm. In addition, the core member 30 was formed by winding the sheet-like composite magnetic body 32 (see FIG. 3) a plurality of times around a portion of the cable 70 near the inner surface of the housing 60. The core member 30 had a ring core shape with an outer diameter of 25 mm, an inner diameter of 12 mm, and a length of 24 mm. The relative magnetic permeability of the composite magnetic body 32 of the core member 30 had the frequency characteristics shown in FIG.

  A horizontal polarization component of noise radiated from the cable 70 to which the noise filter 10 is attached in accordance with the operation of the power supply device 50X was measured with a horn antenna (not shown). The measurement results are shown in the graph “after applying noise filter” in FIG.

  As understood from FIG. 12, the noise suppression effect by the noise filter 10 was confirmed for noise of all wavelengths from 500 MHz to 3 GHz. In particular, a noise suppression effect of about 10 dB was confirmed in all frequency bands of 600 MHz or higher.

10, 10A, 10B Noise filter 20, 20A Shield member 22, 22A Connected portion 24A Mounted portion 26, 26A Protruding portion 30, 30A Core member 32 Composite magnetic body 322 Binder 324 Soft magnetic powder 40, 40X AC power source 42X DC power source 50 Inverter device (power supply device)
50X step-down chopper power supply (power supply)
510, 510X Rectifier circuit 530 DC power supply 540X Switching frequency generation circuit 550 Control circuit 552 PWM circuit 560 DC / DC converter 570, 570X Drive circuit 590 Inverter main circuit 590X Step-down chopper circuit 60 Housing 62 Passing hole 64 Inner surface 66 Outer surface 70 Cable 702 Inner end 706 Outer end 710 Inner portion 720 Passing portion 730 Outer portion 732 Housing side portion 734 Intermediate portion 736 Load side portion 74 Coated conductor 742 Conductive wire 744 Insulation coating 80, 80X Load 86 Support base 88 Floor surface

Referring to FIGS. 1 and 2, the noise filter 10 includes a shield member 20 made of a conductor such as copper, aluminum, and conductive rubber, and a core member 30 made of a composite magnetic body 32. Each of the shield member 20 and the core member 30 is attached to the cable 70 and has a generally cylindrical shape.

Referring to FIGS. 2 and 3, the core member 30 is adjacent to the shield member 20 along the cable 70. Specifically, according to the present embodiment, in the noise filter 10, the shield member 20 and the core member 30 are adjacent to each other with a portion in which the passage hole 62 of the housing 60 is formed , surrounding the cable 70. ing.

Claims (7)

A noise filter for suppressing noise emitted from the cable,
One end of the cable is connected to a power supply device housed inside the housing, and the other end of the cable is located outside the housing,
The noise filter includes a shield member made of a conductor and a core member made of a composite magnetic material,
The shield member surrounds the cable, and extends outside the housing along the cable so as to be separated from the housing;
The core member surrounds the cable and is adjacent to the shield member along the cable;
The composite magnetic body includes a binder and soft magnetic powder dispersed in the binder,
The imaginary component μ ″ of the complex magnetic permeability of the composite magnetic body is a noise filter that is 1 or more and 50 or less over a frequency band from 500 MHz to 3 GHz. The noise filter according to claim 1,
The housing is made of a conductor,
The shield member is a noise filter in contact with the housing. The noise filter according to claim 1 or 2,
The core member is a noise filter in contact with the shield member. The noise filter according to any one of claims 1 to 3,
The shield member has a connected part and a protruding part,
The connected part is connected to the housing;
The protruding portion is a noise filter that is located outside the casing and protrudes away from the casing. The noise filter according to claim 4,
A passage hole is formed in the housing,
The connected portion is located inside the passage hole;
The noise filter, wherein the core member is at least partially surrounded by the connected portion. A noise filter according to any one of claims 1 to 4,
The noise filter, wherein the core member is located at least partially inside the housing. A noise filter according to any one of claims 1 to 4,
The noise filter, wherein the core member is located outside the casing and is further away from the casing than the shield member.

Images