CN117476273A - Cable and electric equipment using same - Google Patents

Abstract

The invention discloses a cable and electric equipment using the same. The cable comprises at least one pair of wires which extend in parallel in the same direction and are insulated from each other, and two wires in each pair of wires are respectively wound and advanced in the cable extending direction and are opposite in winding direction. When the power is on, the current directions in each pair of wires are opposite, so that the directions of the induced magnetic fields generated by the two wires in each pair of wires are opposite, and the reduction of the magnetic field around the cable is realized. The invention can eliminate the surrounding magnetic field caused by the current in the cable in a plurality of application scenes, thereby achieving the effect of reducing the influence on the physical health of people around the cable and the magnetic field interference on other surrounding devices.

Description

Cable and electric equipment using same

Technical Field

The invention belongs to the field of electricity, and particularly relates to a cable capable of reducing magnetic field strength and electric equipment adopting the cable.

Background

Since the invention of electricity, people have been free from the technology of electricity, and the surroundings have been surrounded by various application scenes using electricity. From household appliances to electric vehicles of the present, the utilization of different electricity is not carried out.

However, while enjoying power, people are also experiencing interference and pollution from the power. The various electrical devices are also subject to interference from other electrical devices.

Shielding electromagnetic interference shielding electromagnetic fields is a very common technical approach. But effective electromagnetic field shielding is not easy.

Examples of the related industries of electric vehicles are: with the rise of electric vehicles, charging piles and charging stations equipped with several charging piles are widely used. The charging pile here includes an ac charging pile and a dc charging pile, especially a high-power dc charging pile.

The power of the charging pile here ranges from 5KW up to 600KW of direct current. For high power charging piles, the voltage is typically 380V, the current is 0-700A, or even greater. These currents flow through the conductors inside the charging post device, the charging conductors until the charging gun creates an electromagnetic field to the surroundings. This is the strength of the electromagnetic field that is much higher than that produced by a typical household wire.

Unlike high frequency electromagnetic fields, magnetic fields generated by direct current or alternating current below 100Hz cannot be shielded by metal sleeves. These magnetic fields are present, although they must be limited to the relevant international standards. In particular a direct magnetic field, whose negative influence on humans is even poorly defined. Their negative effects are present.

The data shows that if the current is 5A and the distance from the wire is 1 meter, the magnetic field strength is 1 microtesla. This is the amount of current that is normally reached by a household appliance. If the current is 500A, the magnetic field strength is 100 microtesla. This magnitude of intensity is then the amount of current generated by the charging conducting wire inside the charging post or the charging wire connecting the charging gun.

It is believed that exceeding 0.4 microtesla is considered to be unfavorable to humans. The magnetic field produced by the high voltage line has a safety value of 0.4 microtesla above which children will be at risk of illness, in particular leukemia.

Particularly for transmission lines (low voltage, medium voltage and high voltage) passing through residential areas, strong electric and magnetic field disturbances are brought about by pedestrians under the transmission line. These power lines must be remote from pedestrians and populated areas. The low-voltage electric wire (6-10 KV) of the overhead 380V determined by the method passes through a residential area and cannot be lower than 6 m, and the medium-voltage electric wire (6-10 KV) passes through the residential area and cannot be lower than 6.5 m. The high voltage line of 330KV can not be lower than 8.5 m when passing through a residential area.

So far, the current situation that the induction magnetic field or the electric field generated by the cable around cannot be shielded by a metal shielding sleeve or a shielding net due to low frequency and even constant direct current exists in the prior art that no corresponding technology is used for eliminating the induction magnetic field around the cable. Therefore, it is necessary to design a cable that can attenuate such constant or low frequency magnetic fields.

Disclosure of Invention

The invention aims to provide a cable which purely transmits current from one end to the other end without reverse backflow current, the current is transmitted in the cable, the intensity of a magnetic field generated around the cable can be greatly reduced, and the problem of magnetic field interference caused by current conduction to the surroundings is fundamentally solved.

To achieve the above object, the present invention provides a cable, wherein the cable includes at least one pair of wires extending in parallel in the same direction and insulated from each other, and two wires of each pair of wires are wound in respective advancing and opposite winding directions along the extending direction of the cable. When the cable is electrified, the current directions in each pair of wires are opposite, so that the directions of the induced magnetic fields generated by the two wires in each pair of wires are opposite, and the conditions that the strength of the magnetic field generated by the periphery of the cable is reduced, and even the magnetic fields are mutually counteracted are realized.

In a preferred embodiment, each pair of said wires are electrically connected to each other at both ends.

In a preferred embodiment, each pair of said conductors is arranged such that the magnitude of the respective induced magnetic fields generated by the two conductors differ by no more than 5% after energizing. This means that the remaining non-cancelled magnetic field can be reduced to less than 5% of the magnetic field generated by the single wire, even to zero.

In a preferred embodiment, in a pair of the wires, one of the wires is wound coaxially around the other wire in the wire extending direction.

In a preferred embodiment, each pair of said wires is arranged such that the number of turns per unit length is the same

In a preferred embodiment, one of the wires is less resistive than the other wire.

In a preferred embodiment, one of the wires is larger than the cross-sectional area of the other wire.

In a preferred embodiment, the cable further comprises a core around which at least one of the wires of a pair of wires is wound.

In a preferred embodiment, the cross section of the core strip comprises a circle and a regular polygon.

In a preferred embodiment, the cable further comprises a shielding layer, which encloses all of the conductors.

In a preferred embodiment, the shielding layer is a metal layer or a metal mesh layer.

In a preferred embodiment, the wire is a single conductor wire.

According to another aspect of the present invention, there is also provided a powered device having a cable for power transmission, wherein the cable is a cable as described above.

In a preferred embodiment, the powered device is a device having a power greater than 1 kw.

In a preferred embodiment, the electrical equipment is a charging pile, an electric automobile, a magnetic levitation train, a household appliance and the like.

In a preferred embodiment, the powered device is a charging peg having a charging cord made of the cable.

The invention creatively provides that the wires in the cable are divided into a pair of pairs, and the two wires in each pair of wires are wound in opposite directions, so that the induction magnetic fields generated by each pair of wires when conducting current are mutually weakened or even completely counteracted, the influence on surrounding organisms and electrical equipment can be weakened, and the environmental protection of the product is greatly improved. Meanwhile, the invention is used, because the cable almost generates no magnetic field to the surrounding, especially for low-voltage transmission lines which are close to pedestrians, expensive overhead cables are not required to be arranged away from the residential area, and the cable can be directly adjacent to the residential area or buried underground.

Drawings

FIG. 1 is a schematic view of the cable of the present invention;

FIG. 2 is a schematic structural view of a pair of conductors of the cable of the present invention;

FIG. 3 is a schematic cross-sectional view of the cable of the present invention;

fig. 4 is a schematic view of a winding structure of a pair of wires in the cable of the present invention;

fig. 5 is a partial axial cross-sectional schematic view of a pair of conductors in the cable shown in fig. 4.

Fig. 6 is a schematic view of a charging stake employing the cable of the present invention.

Detailed Description

The following detailed description of various embodiments of the present invention will be provided in connection with the accompanying drawings to provide a clearer understanding of the objects, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the invention, but rather are merely illustrative of the true spirit of the invention.

In the following description, for the purposes of explanation of various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. One skilled in the relevant art will recognize, however, that an embodiment may be practiced without one or more of the specific details. In other instances, well-known devices, structures, and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" and variations such as "comprises" and "comprising" will be understood to be open-ended, meaning of inclusion, i.e. to be interpreted to mean "including, but not limited to.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally employed in its sense including "or/and" unless the context clearly dictates otherwise.

In the following description, for the purposes of clarity of presentation of the structure and manner of operation of the present invention, the description will be made with the aid of directional terms, but such terms as "forward," "rearward," "left," "right," "outward," "inner," "outward," "inward," "upper," "lower," etc. are to be construed as convenience, and are not to be limiting.

Referring to fig. 1-5, the cable of the present invention that can reduce the strength of an electromagnetic field will be described. As shown in fig. 1, the cable includes at least one pair of wires 1 extending in parallel in the same direction and insulated from each other. Only a pair of wires 1 is shown here for clarity. The two wires 11 and 12 of each pair of wires 1 are wound in opposite directions. For example, the wire 11 (shown by a solid line) is wound in a counterclockwise direction, and the wire 12 (shown by a broken line) is wound in a clockwise direction. That is, the wire 11 and the wire 12 correspond to two solenoids having opposite winding directions. The wires 11 and 12 may be coaxial (as shown in fig. 1 and 4) or may be adjacent to each other (as shown in fig. 2). Each pair of wires 1 is electrically connected to each other at both ends. That is, one end of each pair of wires 1 is electrically connected to each other at the head end a of the cable, and the other end is electrically connected to each other at the tail end B of the cable. The electrical connection may be made at the time of manufacture or at the time of use. When the electric connection is completed in use, the two wires can be directly welded or connected to the same connecting terminal, or the two wires are connected together and then connected to the connecting terminal.

When energized, current I flows from terminal a to terminal B, which corresponds to the opposite direction of current due to the opposite winding direction of wire 11 and wire 12 (see fig. 4), and thus the induced magnetic fields generated by wire 11 and wire 12 are opposite according to the ampere right-hand screw rule. That is, the N pole of the induced magnetic field generated by the wire 11 is at the B terminal, and the N pole of the induced magnetic field generated by the wire 12 is at the A terminal. Thus, the induced magnetic fields generated by the wires 11 and 12 cancel each other. Since the wires 1 in the cable are distributed in pairs, the induced magnetic fields substantially cancel each other out; thus, the cable as a whole is substantially free of magnetic fields, thereby greatly reducing the influence on surrounding living things (e.g., people) and electrical equipment and improving the environmental protection of the product.

As shown in fig. 3 to 5, the cable includes 3 pairs of wires 1, each pair of wires 1 being composed of two wires 11 (inner one, hereinafter referred to as inner wire) and 12 (outer one, hereinafter referred to as outer wire) of substantially the same thickness and length. It should be understood that the number of conductors of the cable of the present invention is not limited to 3 pairs, but may be 1 pair, 2 pairs or more than 4 pairs. The surfaces of the inner conductor 11 and the outer conductor 12 are each provided with an insulating layer (not shown). The insulating layer is typically relatively thin. Preferably, the inner conductor 11 and the outer conductor 12 may be enameled wires to reduce the outer diameter of the conductors, and thus the outer diameter of the cable, and reduce the cost. The inner wire 11 is wound around the core bar 10 in a counterclockwise direction, and the outer wire 12 is wound around the inner wire 11 in a clockwise direction, and the arrow in fig. 3 indicates the winding direction. Fig. 4 shows the current flow on the inner conductor 11 and the outer conductor 12 when the current I flows from a to B. As can be seen from fig. 4, the current flow direction of the inner conductor 11 and the outer conductor 12 is opposite, so that the induced magnetic fields generated by the inner conductor 11 and the outer conductor 12 are opposite according to the ampere right-hand screw rule.

In this embodiment, the inner conductor 11 is wound around the core 10. The cross section of the core 10 is generally circular, but may also be regular polygons, such as regular triangles, squares, regular pentagons or regular hexagons, etc. The diameter of the core 10 (corresponding to the coil diameter of the inner conductor 11) is generally not too large (e.g., below 0.5 mm) to avoid too thick a cable. It should be appreciated that in other embodiments, the core 10 may be omitted, for example, the inner wire 11 may be wound in a counter-clockwise direction to resemble a coil spring, and the outer wire 12 may then be wound directly around the inner wire 11 in a clockwise direction.

In order to achieve the purpose of completely or substantially completely canceling the magnetic fields generated by the inner conductor 11 and the outer conductor 12, that is, the magnitude of the induced magnetic fields generated by the inner conductor 11 and the outer conductor 12 are the same or substantially the same (e.g., within 5% of each other), it is necessary to make the magnitudes of the currents in the inner conductor 11 and the outer conductor 12 substantially the same. Since the inner conductor 11 and the outer conductor 12 are connected in parallel, the resistances are the same if the currents are the same. In the present embodiment, the outer wire 12 is wound around the inner wire 11, and thus, the length of the outer wire 12 may be greater than the length of the inner wire 11. According to the resistance formula r=ρl/S, the resistances of the inner wire 11 and the outer wire 12 can be made the same by changing the resistivity ρ and/or the wire cross-sectional area S of the two. Specifically, in the case where the wire cross-sectional areas S are the same, the resistivity of the outer wire 12 is smaller than that of the inner wire 11, i.e., conductive materials of different resistivity may be used for the inner wire 11 and the outer wire 12; whereas in the case where the resistivity ρ is the same, the cross-sectional area of the outer conductor 12 is larger than that of the inner conductor 11, i.e., the inner conductor 11 and the outer conductor 12 may use conductors of different thicknesses or shapes.

Generally, the inner and outer leads 11 and 12 are wound in opposite directions in a tightly wound manner in the axial direction, i.e., adjacent turns are in close proximity, so that the number of windings (i.e., the number of turns) of the inner and outer leads 11 and 12 per unit length is substantially the same, so that the magnitude of the generated magnetic field is also substantially the same, and the manufacturing is facilitated.

In the illustrated embodiment, the inner conductor 11 and the outer conductor 12 are each single-conductor, i.e., are formed of one copper wire having a relatively large wire diameter (e.g., 0.5 mm or more). It should be understood that the inner and outer wires 11, 12 may also be multicore wires, i.e. made of a plurality of copper wires of smaller wire diameter (e.g. less than 0.1 mm).

The cable may further comprise a shielding layer 2, said shielding layer 2 surrounding all wires 1 for shielding high frequency electromagnetic interference. The shielding layer 2 may be a metal layer or a metal mesh layer or the like. The outside of the shielding layer 2 is wrapped with a protective layer (or sheath) 3. The material of the protective layer 3 may be a plastic type such as polyvinyl chloride (PVC), polyethylene (PE), polyperfluoroethylene propylene (F46), polyolefin, or a rubber type such as Chlorinated Polyethylene (CPE), chlorosulfonated polyethylene (CSM), neoprene, silicone rubber, or the like. Typically, the thickness of the shielding layer 2 is much smaller than the thickness of the protective layer 3.

The cable of the present invention is quite different from conventional twisted pair cables in that a pair of wires are twisted together in the same direction and the direction of the wires forming an axial wrap is uniform. When the current directions of the two wires are the same, the surrounding magnetic fields generated by the currents in the two wires are overlapped; only when the current directions of the two wires are opposite, the magnetic fields generated by the currents in the wires are weakened mutually. However, when the current flows in the two wires in opposite directions, no current flows from one end to the other end. In contrast, when the pair of wires of the cable is electrified, current flows from one end to the other end, but the wires are wound and advance in opposite directions, so that the effect of making the current directions of the two wires opposite is achieved in space, and further the generated magnetic fields are mutually weakened or even offset. Particularly in the case of high currents, the high currents generate magnetic fields with high intensity around the high currents, and the magnetic fields can be mutually weakened or even counteracted by winding the two wires in opposite directions. That is, the cable of the present invention may be used in high power (e.g., 1kw or more) electric devices such as charging piles, electric vehicles, magnetic levitation trains, home appliances, etc., for transmitting electric power.

Taking a charging pile as an example, as shown in fig. 6, a cable 102 from a distribution box (not shown) to a charging pile body 100 and between the charging pile body 100 and a charging gun 101 may use the cable of the present invention. Therefore, the magnetic field intensity of the charging pile device for surrounding organisms and electrical equipment can be greatly reduced, and meanwhile, the interference on the charging pile device and a display screen arranged in the charging pile is also directly reduced.

Likewise, the cable for transmitting large current inside the electric automobile and the power wire of a high-power household appliance (such as an electric hair dryer, an electric water heater, an air conditioner, a microwave oven or a smoke exhaust ventilator) can be used by the cable of the invention, so that the influence on the electromagnetic field intensity of surrounding living things and electric equipment is reduced, and the environmental protection is greatly improved.

The invention is also of interest for the application of low and medium voltage power lines, i.e. power lines from substations to subscribers in cells, shops etc. Low and medium voltage power transmission line systems are expensive because the power transmission lines can have deleterious effects on the surrounding environment, including strong induced electric and magnetic fields, which need to be located very high and far from populated areas. By using the invention, the induced magnetic field can be almost eliminated at a short distance. From the perspective of eliminating the magnetic field, the invention can lighten the magnetic field interference of the power transmission line system to surrounding residential areas, and simultaneously, the distance between the power transmission line and pedestrians and the residential areas is shortened, so that the power transmission line is not required to be arranged very high and far away from the residential areas, but can be directly adjacent to the residential areas or buried in the ground.

While the preferred embodiments of the present invention have been described in detail, it will be appreciated that those skilled in the art, upon reading the above teachings, may make various changes and modifications to the invention. Such equivalents are also intended to fall within the scope of the claims appended hereto.

Claims (16)

1. A cable comprising at least one pair of wires extending in parallel in the same direction and insulated from each other, both wires of each pair of wires being wound in respective advancing and reversing directions along the direction of extension of the cable.

2. The cable of claim 1, wherein each pair of the wires are electrically connected to each other at both ends.

3. A cable according to claim 1, wherein each pair of said conductors is arranged such that, upon energisation of both said conductors, the respective magnitudes of the induced magnetic fields generated to the surroundings differ by no more than 5%.

4. The cable of claim 1 wherein one of said conductors is coaxially wrapped around the other of said conductors.

5. The cable of claim 4 wherein each pair of said conductors is arranged such that the number of turns per unit length is the same.

6. The cable of claim 4 wherein the resistivity of one of said conductors is less than the resistivity of the other of said conductors.

7. The cable of claim 4 wherein the cross-sectional area of one of said conductors is greater than the cross-sectional area of the other of said conductors.

8. The cable of claim 1 further comprising a core around which at least one of the pair of conductors is wound.

9. The cable of claim 8, wherein the core strip has a circular or regular polygon cross-section.

10. The cable of claim 1, further comprising a shielding layer surrounding all of the conductors.

11. The cable of claim 10, wherein the shielding layer is a metal layer or a metal mesh layer.

12. The cable of claim 1, wherein the conductor is a single conductor.

13. A powered device having a cable for power transmission, characterized in that the cable is a cable according to any one of claims 1-12.

14. The powered device of claim 13, wherein the powered device is a device having a power greater than 1 kw.

15. The powered device of claim 13, wherein the powered device is a charging pile, an electric car, a maglev train, or a household appliance.

16. The powered device of claim 13, wherein the powered device is a charging stake having a charging cord made from the cable.