JPH0542573Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention relates to a power cable used in a switching power supply device, etc., and particularly relates to a technology for reducing radiated noise generated from the power cable.

<<Prior Art>> Cores for common mode choke coils have conventionally been used for the purpose of reducing radiated noise generated from power cables of switching power supplies. This is a ring-shaped core made of ferrite or similar material, and a pair of power wires are wound in phase through this. This is equivalent to inserting a common mode choke coil in the middle of the power cable, attenuating high frequency common mode noise between the two power lines and the ground, and reducing radiation noise generated from the cable.

<<Problem to be solved by the invention>> Some power cables have one ground wire in addition to two power wires. In this way, when a power cable with a ground wire is passed through the core for the common mode choke coil described above, the ground wire is also wound in the same phase as the two power wires.

In a power cable with a ground line, common mode noise generated in the two power lines appears in the ground line as a noise current in the opposite direction. Therefore, if the ground wire is wound in phase with the two power supply wires at the core, the damping effect of the chi-yoke coil on common mode noise cannot be obtained, and therefore the radiation noise generated from the cable cannot be reduced.

This idea was made in view of the conventional problems mentioned above, and its purpose was to reduce radiated noise even for power cables with ground wires through the action of the common mode choke coil. The goal is to

《Means for solving the problem》 Therefore, in this invention, two power supply wires are wound in the same phase around the core of the common mode chiyoke coil, and one ground wire is wound in anti-phase, and these three wires are wound in the opposite phase. The core was integrally covered with an exterior tube, and plugs were connected to both ends of the tube.

<<Operation>> Since the two power supply lines and the ground line are wound in opposite phases to the core, the effect of the chi-yoke coil on the common mode noise current flowing in the opposite direction to the power supply line and the ground line is occurs, reducing noise current. Therefore, radiated noise from the power cable is also reduced.

<<Embodiment>> FIGS. 1 and 2 show a schematic configuration of a power cable according to an embodiment of the present invention. Plugs 2 and 3 are connected to both ends of a cable covered by an integrally molded exterior tube 1. Inside the exterior tube 1 are two power supply lines 4a and 4b and one ground line 5. Of course, these power supply lines 4a, 4b and ground line 5 are also covered wires. A core 6 for a common mode choke coil is housed in an exterior tube 1 along with power wires 4a, 4b and a ground wire 5 in a swollen portion in the middle of this power cable.
The core 6 is made of ring-shaped ferrite, and the two power supply wires 4a and 4b simply pass through the core 6 and are wound in half turns in the same phase. On the other hand, the ground wire 5 makes one turn from the outside to the inside of the core 6,
The power supply lines 4a and 4b are wound in an opposite phase.

In the above configuration, the common mode noise current generated in the power cable is in opposite directions between the power lines 4a and 4b and the ground line 5. For this common mode noise current, the power supply line 4 is connected to the core 6 part.
Since a, 4b and the ground line 5 constitute a common mode choke coil, a damping effect against noise current appears. Therefore, radiation noise caused by high frequency common mode noise is also reduced.

<<Effects of the invention>> As explained in detail above, the power cable according to this invention has a core that is connected to the cable so that a common mode choke coil is formed between two power wires and one ground wire. When this cable is used as a power cable for a switching power supply device, the radiation noise generated from the cable can be significantly reduced compared to conventional cables.

[Brief explanation of the drawing]

FIG. 1 is an external view of a power cable according to an embodiment of the present invention, and FIG. 2 is a partially cutaway view of the same cable. 1... Exterior tube, 2... Plug, 3... Plug, 4a... Power line, 4b... Power line, 5...
Ground line, 6...core.

Claims (1)

[Scope of utility model registration request] Two power wires are wound in the same phase around the core for the common mode choke coil, and one ground wire is wound in the opposite phase, and these three wires and the core in the middle are integrally wrapped in an exterior tube. A power cable that is coated and has a plug connected to each end.