JP2002198680A - Cable noise suppression device for airborne electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable noise suppression device for an airborne electronic equipment which can suppress a radiating noise from a cable between a three- phase AC generator and a switching shunt power circuit, to which power is supplied from the generator, to a required level. SOLUTION: This device includes a three-phase power cable 3 for connecting a three-phase AC generator 1 for airborne electronic equipment and a switching shunt power circuit 2 to which power is supplied from the generator, a conductive inner shield 4 covering the cable, a doughnut ferrite core 6 surrounding a part of the internal shield, and a ferromagnetic outer shield 8 covering the inner shield and the ferrite core. Both the inner shield 4 and the outer shield 8 are grounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable noise suppression device for electronic equipment mounted on an aircraft, which suppresses radiation noise from a cable between a generator and a power supply circuit.

[0002]

2. Description of the Related Art In an electronic device for an aircraft engine, a dedicated three-phase AC generator directly connected to a gear box of the engine and an electronic device for controlling the engine are provided at positions separated by a cable. Further, the electronic device is provided with a switching shunt power supply circuit, and power is supplied from the power supply circuit to each electronic device.

[0003]

In the above-mentioned electronic equipment mounted on an aircraft, an AC current of a relatively low voltage (for example, about 35 V) flows through a cable connecting the dedicated three-phase AC generator and the switching shunt power supply circuit. Radiated noise is generated from this cable.

In order to suppress the radiation noise, the radiation noise has conventionally been generally suppressed by adding a noise suppression circuit to a power supply circuit. However, the power supply circuit of the electronic equipment mounted on an aircraft has not been sufficiently effective.

[0005] Also, there has been proposed means for covering the cable with a metal fiber fabric to form a shield coating, and for grounding the shield coating. However, also in this case, in the aviation engine, the current flows backward from the ground and becomes a noise source, and the noise level cannot be reduced to the noise level required for the electronic device mounted on the aircraft.

The present invention has been made to solve such a problem. That is, the purpose of the present invention is to
Provided is a cable noise suppression device for an airborne electronic device capable of suppressing radiation noise from a cable between a phase alternating current generator and a switching shunt power supply circuit to which power is to be supplied to a level required for an airborne electronic device. It is in.

[0007]

According to the present invention, there is provided a connection between a three-phase AC generator for airborne electronic equipment (1) and a switching shunt power supply circuit (2) to which power is supplied from the generator. Phase power cable (3), conductive inner shield (4) covering the cable, donut-shaped ferrite core (6) surrounding a part of the inner shield, and ferromagnetic covering the inner shield and the ferrite core A cable noise suppression device is provided, comprising a body outer shield (8), wherein both the inner shield and the outer shield are grounded.

[0008] According to a preferred embodiment of the present invention, the inner shield and the outer shield are metal braided wires.

According to the configuration of the present invention, the three-phase power supply cable (3) connecting the three-phase AC generator (1) and the switching shunt power supply circuit (2) to which power is supplied from the three-phase AC generator is electrically conductive. Inner shield made of metal braided wire (4)
, The electromagnetic radiation due to the current flowing through the power cable is suppressed. Further, since a donut-shaped ferrite core (6) surrounding a part of the inner shield is provided thereon, the impedance of the inner shield is increased by the ferrite core, and the common mode current flowing through the inner shield is suppressed. Further, by covering the inner shield and the ferrite core with the outer shield (8) made of a ferromagnetic metal braid, leakage electromagnetic radiation from the inner shield and electromagnetic radiation due to common mode current flowing through the inner shield are suppressed.

Therefore, according to this configuration, the cable (3)
It has been confirmed through experiments that the radiation noise from the vehicle can be suppressed to the level required for airborne electronic equipment.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an airborne electronic device including the cable noise suppression device of the present invention, and FIG. 2 is a schematic circuit diagram of FIG.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a three-phase AC generator directly connected to a gear box of an aircraft engine (jet engine) exclusively for electronic equipment mounted on an aircraft, and reference numeral 2 denotes a power supply from the three-phase AC generator 1. Switching shunt power supply circuit. The switching shunt power supply circuit 2 rectifies the three-phase AC power supplied from the three-phase AC generator 1 to DC, and supplies DC power of a required voltage to each electronic device mounted on the aircraft. .

The cable noise suppression device 10 of the present invention
It comprises a three-phase power cable 3, an inner shield 4, a ferrite core 6, and an outer shield 8. Three-phase power cable 3
Is a three-wire power cable that electrically connects the three-phase AC generator 1 and the switching shunt power circuit 2, and has connectors 7 at both ends, and is connected to the three-phase AC generator 1 and the switching shunt power circuit 2, respectively. It is connected. The inner shield 4 covers the entire surface of the cable 3 and preferably the connector 7
Is a conductive braided wire covering the wire. The present invention is not limited to this, and may be a metal sheet material, expanded metal, or punched metal as long as it has an electromagnetic wave shielding effect. Both ends of the inner shield 4 are grounded to the main body 9a of the aircraft engine 1 or the ground line 9b of the power supply circuit 2.

The ferrite core 6 is a donut-shaped ferrite material surrounding a part of the inner shield 4, and as shown in FIG. 2, forms a kind of coil in a part of the inner shield 4 to increase its impedance. It has become. The ferrite core 6 is formed, for example, by bonding Ni-Zn soft magnetic powder with an organic binder such as an elastomer.

The outer shield 8 is a ferromagnetic metal braided wire covering the inner shield 4 and the ferrite core 6, and both ends thereof are grounded to the main body 9a of the aircraft engine 1 or the earth line 9b of the power supply circuit 2. I have.

FIG. 3 is a diagram showing an embodiment of the present invention.
In this figure, (A) is a conventional example, and (B) is a case provided with the cable noise suppression device of the present invention. In each of the figures, the horizontal axis represents the frequency, and the vertical axis represents the radiation noise level. The broken line in the figure is the level (limit) required for the electronic device mounted on the aircraft, and the waveform in the figure is the measured noise.

From this figure, it can be seen that in the conventional example, about 200 kHz
It can be seen that the noise is not below the limit in the range of about 3 MHz. This is for airborne electronics
This is probably because it is difficult to completely separate the ground from the electronic device, and the current flows backward from the ground to become a noise source. In contrast, in the embodiment of the present invention,
As shown in FIG. 3B, from about 200 kHz to about 3 MHz
It can be seen that in all the measurement frequency ranges including the range of z, the measured value is sufficiently below the limit required for the onboard electronic equipment.

That is, according to the configuration of the present invention, a three-phase power cable 3 connecting between the three-phase AC generator 1 and the switching shunt power circuit 2 to which power is supplied from the three-phase AC generator 1
Is covered with the inner shield 4 made of a conductive metal braided wire, thereby suppressing electromagnetic radiation due to current flowing through the power cable. Further, since a donut-shaped ferrite core 6 surrounding a part of the inner shield is provided thereon, the impedance of the inner shield is increased by the ferrite core to suppress a common mode current flowing through the inner shield. Further, by covering the inner shield 4 and the ferrite core 6 with the outer shield 8 made of a ferromagnetic metal braided wire, it is possible to suppress the electromagnetic radiation caused by the leakage from the inner shield 4 and the common mode current flowing through the inner shield 4. Can be.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0020]

As described above, the present invention relates to a power supply system comprising a dedicated three-phase AC generator, a cable between a generator and a power supply, and a switching shunt power supply circuit, by providing the cable with a noise suppression function by providing a noise suppression function. The combination of the three means makes it possible to satisfy the requirement for electromagnetic compatibility required for electronic devices mounted on aircraft.

Therefore, the cable noise suppression device for an aircraft-mounted electronic device according to the present invention requires the aircraft-mounted electronic device to emit radiation noise from the cable between the three-phase AC generator and the switching shunt power supply circuit to which the power is supplied. It has an excellent effect that it can be suppressed to a certain level.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an airborne electronic device including a cable noise suppression device of the present invention.

FIG. 2 is a schematic circuit diagram of FIG.

FIG. 3 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 3 phase alternating current generator 2 switching shunt power circuit 3 3 phase power cable 4 inner shield (conductive metal braided wire) 7 connector 6 ferrite core 8 outer shield (ferromagnetic metal braided wire) 9a, 9b ground 10 cable noise suppression apparatus

Claims (2)

[Claims] A three-phase power cable (3) for connecting between a three-phase AC generator (1) for an electronic device mounted on an aircraft and a switching shunt power circuit (2) to which power is supplied from the three-phase alternating current generator (1). A conductive inner shield (4) covering the inner shield, a donut-shaped ferrite core (6) surrounding a part of the inner shield, and a ferromagnetic outer shield (8) covering the inner shield and the ferrite core. A cable noise suppression device, wherein both the inner shield and the outer shield are grounded. 2. The cable noise suppression device according to claim 1, wherein the inner shield and the outer shield are metal braided wires.