JP2016072374A - Magnetic material core and cable connector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove both common mode noise and differential mode noise effectively, while hardly causing magnetic saturation even under a large current.SOLUTION: A magnetic material core 30 is incorporated in a cable connector 1 connected to the tip side of a cable 100. The magnetic material core 30 removes noise on the line of a power cable 100 in the inserted state. The magnetic material core 30 includes an annular body 31 having a central opening 311 for inserting the lines 101, 102, 103 of the power cable 100, and inner walls 32, 33 formed continuously to the annular body 31, the inner walls 32, 33 partitioning the lines 101, 102, 103 of the power cable 100. Air gaps 321, 331 are formed in the inner walls 32, 33.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic core for reducing both common mode noise and differential mode noise (normal mode noise) radiated and conducted from a cable or the like, and a cable connector using the same.

  When removing noise radiated and conducted from a cable, a ferrite core (for example, Patent Document 1) may be used.

  Regarding the principle of noise removal of the ferrite core, since the X component of the core itself is dominant in the low frequency region, it functions as an inductor and reflects noise, while in the high frequency region, the R component of the core itself is dominant. Therefore, it is based on functioning as a resistor and converting noise into heat and absorbing it.

  For example, for a two-wire cable for a single-phase power supply, common mode noise can be removed if the two wires are put together through a hole in a ferrite core.

Japanese Patent Laid-Open No. 08-017635

  However, in such a case, the differential mode noise cannot be removed. In order to remove the noise, it is necessary to prepare two cores and pass them through the core holes for each cable. When the number of phases increases, the number of cores increases according to the number of phases, which makes it difficult to reduce the cost. Further, since the signal current is not canceled out, the core is easily magnetically saturated. When the core is magnetically saturated, the noise reduction effect is greatly reduced due to the impedance reduction. In particular, a power cable having a large current value generally does not use a ferrite core as a countermeasure for differential mode noise.

  The present invention was created under the above background, and the object of the present invention is to hardly cause magnetic saturation even under a large current, and effectively eliminates both common mode noise and differential mode noise. It is an object of the present invention to provide a removable magnetic core and a cable connector using the same.

  The magnetic core according to the present invention is a core for removing noise riding on a cable or the like in a state where a cable or a bus line is inserted, and an annular main body having a central opening for inserting the cable or the like And an inner wall part that is formed continuously with the annular main body part and partitions lines of the cable or the like, and an air gap is formed in the inner wall part.

  According to the above invention, the cable or the bus line is inserted into the central opening of the annular main body portion, and the lines taken out from the end portion of the cable or the like are partitioned by the inner wall portion. Alternatively, when the current of the power source is supplied, noise on the cable or the like is removed as follows.

  As for common mode noise, each magnetic flux caused by a noise current flowing in the same direction in two lines included in a cable or the like is absorbed by the annular main body. On the other hand, as for differential mode noise, each magnetic flux generated by the signal current and the noise current flowing in the opposite directions in the two lines included in the cable or the like is absorbed by the inner wall portion. As a result, both common mode noise and differential mode noise riding on a cable or the like can be effectively removed. Since the noise removal effect can be obtained without combining various types of ferrite cores unlike the conventional one, a cost effect can be obtained.

  Further, since an air gap is formed in the inner wall portion of the magnetic core, magnetic saturation hardly occurs even under a large current. In addition, the ferrite core provided with the air gap in the annular portion is likely to undergo mode conversion from the differential mode to the common mode. However, in the present invention, there is no air gap in the annular main body portion and there is an air gap only in the inner wall portion. Therefore, mode conversion is difficult to occur. In these respects, a high noise removal effect can be obtained. In particular, since it is possible to suppress the occurrence of common mode noise with high radiation efficiency, it is possible to reduce noise.

  Preferably, the air gap is formed in a central portion of the inner wall portion.

  According to the above aspect of the invention, since the circuits viewed from the left and right sides of the core (signal input side output side) are all balanced circuits, no unnecessary voltage is generated in the circuit, and mode conversion does not occur accordingly. A high noise removal effect can be obtained. If there is an air gap in the annular main body, it becomes unbalanced with respect to the return noise, so that the noise that is not originally radiated in the differential mode is converted into the common mode and radiated. Since this situation is avoided, there is a great merit in reducing noise.

  When the magnetic core is used for a cable or a bus line of an electronic device, it is preferable that the magnetic core is arranged in a casing of the electronic device.

  According to the invention of the above embodiment, since the magnetic core is close to the noise generation source of the electronic device, a high noise removal effect can be obtained, and there is a great merit in reducing the noise.

  The cable connector which concerns on this invention is a connector used for the cable for power supplies or signals, Comprising: The said magnetic body core is provided.

  According to the above invention, even when a large current flows through a power cable or the like, common mode noise and differential mode noise are effectively removed, and it is possible to easily take EMC countermeasures for electronic devices / electric devices. .

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the case where it is used for a vehicle-mounted electronic device is mentioned as an example.

  In the figure, reference numeral 1 denotes a cable connector, which in the present example is a resin plug connected to the distal end side of a high-voltage three-phase three-wire power cable 100. Connection terminals 20A, 20B, and 20C, which are plug blades, are provided at the tip of the plug body 10. A-phase, B-phase, and C-phase lines 101, 102, and 103 drawn from the front end side of the power cable 100 are electrically connected to the connection terminals 20A, 20B, and 20C, respectively. A magnetic core 30 is embedded in the plug body 10 in order to take EMC countermeasures for electrical equipment.

  The magnetic core 30 is a flat type core that removes noise on the cable 100 while the power cable 100 is inserted, and has a central opening 311 for inserting the lines 101, 102, and 103 of the power cable 100. And the inner wall portions 32 and 33 that are connected to the annular body portion 31 and partition the lines 101, 102, and 103 in the power cable 100. The intervals between the inner wall portions 32 and 33 in the opening 311 are made equal, and air gaps 321 and 331 are formed in the central portions of the inner wall portions 32 and 33, respectively.

  In this example, ferrite is used as the material of the magnetic core 30, and it is used for the power cable 100 in which a three-phase alternating current of 20A or more flows.

  The frequency characteristics of the magnetic core 30 configured as described above are as shown in FIG. 4, and the impedance is higher than that of a single wire (W / O ferrite). Noise removal effect can be obtained not only for common mode noise but also for differential mode noise.

  The basic principle by which the noise removal effect can be obtained by the magnetic core 30 will be described with reference to FIG. Here, for convenience of explanation, the noise on the lines 20A and 20B included in the power cable 100 will be described.

  As for the common mode noise, as shown in FIG. 5 (a), the noise current A flowing through the line 20A and the noise current B flowing through the line 20B have the same direction. The middle one-dot broken line indicates the direction of the magnetic flux due to the noise current A, and the broken line in the figure indicates the direction of the magnetic flux due to the noise current B) passes through the annular main body 31 of the magnetic core 30 and is absorbed in this process. On the other hand, as for differential mode noise, as shown in FIG. 5B, the direction of the noise current A flowing through the line 20A and the noise current B flowing through the line 20B are opposite to each other. (A dashed line in the figure indicates the direction of the magnetic flux due to the noise current A, and a broken line in the figure indicates the direction of the magnetic flux due to the noise current B) passes through the inner walls 32 and 33 of the magnetic core 30 and is absorbed in this process. .

  The same applies to the noise on the lines 20B and 20C included in the power cable 100.

  As described above, the common mode noise and the differential mode noise related to the noise current flowing in the power cable 100 can be effectively removed. Since the noise current is smaller than the signal current, it is not necessary to consider the maximum allowable current flowing through the power cable 100.

  In addition, since the air gaps 321 and 331 are formed in the inner wall portions 32 and 33 of the magnetic core 30, magnetic saturation hardly occurs even when a large current flows through the power cable 100. In addition, in the ferrite core having a normal air gap, mode conversion from the differential mode to the common mode is likely to occur. However, in the case of the magnetic core 30, the annular body portion 31 has no air gap and the inner wall portions 32, 33. Since there are only air gaps 321 and 331, mode conversion is difficult to occur.

  FIG. 6 shows the impedance of the mode conversion for converting from the differential mode to the common mode, and this is also clear from the fact that the impedance of the magnetic core 30 of the present example is set higher than 1000Ω.

  The fact that the air gaps 321 and 331 are formed in the inner wall portions 32 and 33 is one of the reasons that mode conversion is difficult to occur. If the air gaps 321 and 331 are formed in the annular main body 31, on the contrary, mode conversion is facilitated, and common mode noise may be emitted.

  Furthermore, the fact that the air gaps 321 and 331 are set to the optimum values (1 mm in this example) is one of the reasons that mode conversion is difficult to occur. The shorter the size of the air gaps 321 and 331, the higher the noise reduction effect against differential mode noise. On the other hand, the longer the size, the higher the magnetic saturation current value, as well as the mode from differential mode to common mode. Conversion is unlikely to occur.

  In addition, since the circuits viewed from the left and right sides of the magnetic core 30 (signal input side output side) are all balanced circuits, no unnecessary voltage is generated in the circuit, and mode conversion hardly occurs in this respect. It has become. If there is an air gap in the annular main body 31, it becomes unbalanced with respect to the return noise, so that noise that is not originally radiated in the differential mode is converted into the common mode.

  Since the magnetic core 30 is unlikely to undergo mode conversion as described above, it is possible to avoid a situation in which noise that is not originally radiated in the differential mode is converted into the common mode and radiated. Therefore, it is possible to suppress the occurrence of common mode noise having high radiation efficiency, and to reduce noise.

  When the cable connector 1 provided with the magnetic core 30 having such characteristics is used in an in-vehicle electronic device, it is possible to easily take EMC / noise countermeasures for the electronic device.

  However, the magnetic core 30 may be redesigned into a shape as shown in FIG. 7 (including making the opening in the core a round shape or the like). Although the example shown in FIG. 7 is for a single phase, it can also be applied to multiphases of three or more phases, so the design may be changed as appropriate according to the number of phases. Further, the usage form in which the magnetic core 30 is built in the cable connector 1 may be used.

  FIG. 8 shows a practical example in which the magnetic core 30 is inserted into the power cable 100 of the electronic device 2 such as an inverter ECU or a DC-DC converter ECU. FIG. 8A shows an example in which the electronic device 2 is arranged inside the casing 21, and FIG. 8B shows an example in which the electronic device 2 is arranged outside the casing. In particular, in the example shown in FIG. 8A, since the magnetic core 30 is close to the noise generation source 22 (for example, a switching circuit board), a high noise removal effect can be obtained, and the noise is reduced. There is a big merit in lowering.

  In addition, about the magnetic body core which concerns on this invention, it is not limited to the said embodiment, Noise removal is possible not only about the line of a power cable but the line of a signal cable similarly. Further, the present invention can be similarly applied not only to the form inserted into the cable but also to the form inserted into the bus line. Permalloy, amorphous, etc. can be used for the material of the magnetic core, and the shape, dimensions, material, etc. are appropriately designed according to the application target (current flow / mode, noise level, frequency, etc.) It is preferable to change (including changing the shape of the annular main body to a ring shape instead of a flat shape). About the cable connector which concerns on this invention, the kind may be a socket etc., and as long as the line of a cable penetrates, it will not ask about the positional relationship of a magnetic body core.

It is a figure for demonstrating embodiment of this invention, Comprising: It is a schematic plan view of a cable connector. It is a schematic side view of the cable connector. It is the figure showing the shape of the magnetic body core used for the cable connector, (a) is a front view, (b) is a plan view, (c) is a rear view, (d) is a left side view, e) is a right side view. It is a graph which shows the impedance frequency characteristic of the same magnetic body core. It is explanatory drawing for demonstrating the principle of the noise removal of the same magnetic body core for every mode. 6 is a graph showing impedance of mode conversion from a differential mode to a common mode in the same magnetic core. It is a typical perspective view for demonstrating the modification of the shape of a magnetic body core. It is a schematic diagram for demonstrating the modification of use of a magnetic body core, Comprising: (a) is an example with the magnetic body core arrange | positioned in an electronic device, (b) is a magnetic body core arrange | positioned outside an electronic device. An example is shown.

DESCRIPTION OF SYMBOLS 1 Cable connector 100 Power cable 101,102,103 Line 30 Magnetic body core 31 Annular body part 311 Center opening 32,33 Inner wall part 321 and 331 Air gap

Claims (4)

  A core for removing noise riding on the cable or the like in a state where the cable or bus line is inserted, and an annular main body having a central opening for inserting the cable or the like, and the annular main body A magnetic core comprising: an inner wall portion that is formed in a row and that partitions lines of the cable and the like, and an air gap is formed in the inner wall portion.   2. The magnetic core according to claim 1, wherein the air gap is formed at a central portion of the inner wall portion.   3. The magnetic core according to claim 1, wherein the magnetic core is inserted into a cable or a bus line of the electronic device, and is disposed in a casing of the electronic device. A cable connector used for a power supply or signal cable, wherein the magnetic core according to claim 1 or 2 is provided.

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