KR200209405Y1 - Broadband EMC Filter - Google Patents

Abstract

Disclosed is a broadband Electro-Magnetic Compatibility (EMC) filter that filters out unwanted electromagnetic waves induced on an AC power line. The conventional power filter has a problem that the load connected to the filter malfunctions because the attenuation characteristic is not constant and the attenuation is less than 20 dB according to the frequency band of the unnecessary electromagnetic wave. The present invention to solve this problem is a varistor to protect the load from surge voltage, through-type capacitor for bypassing transients and unwanted electromagnetic waves to ground, and cores to increase the input impedance of the load It consists of. Therefore, the present invention has the advantage of being able to attenuate 20 dB or more over almost all frequency bands of the unwanted electromagnetic waves induced on the AC power input and effectively remove the surge voltage than the prior art.

Description

Electromagnetic Compatibility filter for wide band

The present invention relates to an EMC (Electro-Magentic Compatibility) filter that removes unwanted electromagnetic waves induced in AC power lines and protects the load from discontinuous surge voltages.

As the use of high frequency devices such as CPUs for high-speed switching or portable wireless terminals with operating frequencies above 1 GHz expands, power lines input to the vessel control equipment or controllers of various automation facilities are exposed to these unwanted electromagnetic waves, resulting in malfunction of the equipment. I'm making it.

In order to remove these unwanted electromagnetic waves induced on a power line, a line filter or an isolation transformer has been conventionally used. However, insulated transformers are expensive and generally use low-cost line filters. The operation of the conventional line filter will be briefly described with reference to FIG. 1.

1 is a diagram showing the circuit configuration of a conventional line filter.

In the conventional line filter, as shown in FIG. 1, the transient voltage protection part 11 is provided at an input terminal. The toroidal core 12 is connected to the output side of the transient voltage protection unit 11. The ripple voltage control unit 13 is provided at the output terminal. These elements are shielded from external electromagnetic waves by being configured inside a conductive enclosure 14 that is grounded. First, when AC power including an unwanted electromagnetic wave and a surge voltage is input from the input terminal, the film capacitor of the transient voltage protection part 11 relaxes the surge voltage. In addition, the toroidal core 12 increases the input impedance of the load connected to the output terminal, and the resistors and capacitors of the ripple voltage removing unit 13 remove the high frequency ripple voltage.

However, in the conventional line filter as described above, when an unwanted electromagnetic wave of 70 MHz to 2 GHz is artificially applied to an input terminal, the characteristic of the filter is lost and conducted to the load side as it is over an arbitrary band of the unwanted electromagnetic wave. In addition, the conventional line filter has an attenuation of 20 dB or less, the capacitance between the windings of the toroidal core and the inductor of the coil itself generate parallel resonance, and the inductance component included in the lead wire of the aluminum capacitor in the output stage is a capacitor. It is not possible to effectively attenuate the problem of generating its own capacitance and series resonance.

Therefore, an object of the present invention is to provide a wide band EMC (flat attenuation characteristic) of 20 dB or more with respect to undesired electromagnetic waves from 70 MHz to 2 GHz and surge voltage generated when switching a power supply or closing a relay contact, and does not generate a series / parallel resonance point on a power line. Electro-Magnetic Compatibility) filter.

1 is a diagram showing a circuit configuration of a conventional line filter.

2 is a view showing a circuit configuration of a broadband EMC filter according to the present invention.

3 is a view showing the arrangement of each component constituting the present invention.

* Explanation of symbols for main parts of the drawings

11: transient voltage protection unit 12: toroidal core (Toroidal Core)

13: ripple voltage removing unit 14: enclosure

21: transient voltage protection part 22: through capacitor part

23: toroidal core 24: ferrite core (Ferrite)

25: enclosure

Broadband EMC filter according to the present invention for achieving the above object is a filter for removing the unwanted electromagnetic waves induced in the two-phase AC power supply to the load, the electrostatic voltage, surge voltage induced in the input power And a transient voltage protection unit configured to attenuate the continuous / discontinuous transient voltages and output them to the next stage. In addition, the present invention flatly attenuates the unwanted electromagnetic waves from 70 MHz to 20 GHz induced by the transient voltage attenuated by more than 20 dB to the next stage and includes a through-type condenser mounted directly on the enclosure. In addition, the present invention includes a troidal core and a ferrite core that cancels parallel resonant phenomena generated from the troidal core, thereby outputting a power to which the unwanted electromagnetic waves are attenuated and increasing the input impedance of the load. The core part and these components include an enclosure shielded from external electromagnetic waves and grounded.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view showing a circuit configuration of a broadband EMC filter according to the present invention. As shown in the drawing, the present invention includes a transient voltage protection part 21 for relieving the surge voltage induced in the input power supply at the input terminal to protect the load from the surge voltage. The transient voltage protection part 21 is connected with a through-type capacitor part 22 for bypassing unnecessary electromagnetic waves, static electricity and surge current to the ground side. The toroidal core 23 and the ferrite core 24 which increase the input impedance of the load are connected to the through capacitor 22. These components are all embedded inside the enclosure 25 which is grounded, effectively shielding external unwanted electromagnetic waves.

In the preferred embodiment of the present invention (see Fig. 3), the transient voltage protection part 21 uses a varistor of the Marcon TNR 15G model, and the through type capacitor part 22 is 250V (AC) 5㎌ 15A specification. Cornell-Dubilier's penetrating capacitor was used. In addition, the ferrite core 24 is a product of DM steward of Φ 14mm (inner diameter), Φ: 30mm (outer diameter), L: 30mm (length) specification, and the enclosure 25 is 170 mm x 110 mm x 70 mm (size) and steel plate (material) specification.

3 is a view showing the arrangement of each component constituting the present invention.

Operation of the broadband EMC filter according to the present invention configured as described above will be described in more detail with reference to FIGS. 2 and 3.

First, three varistors of the transient voltage protection unit 21 are connected between two input terminals, a first input terminal and a ground terminal, and a second input terminal and a ground terminal, respectively. Each varistor is stronger than the conventional film capacitor, and has 50ns of instantaneous overvoltage (EFT), such as surge voltage and electrostatic voltage, included in the AC voltage input through the input terminal. Reduce the response speed. Then, the through capacitor 22 attenuates the transient current and the EFT-free electromagnetic wave of the power supply passing through the transient voltage protection part 21 evenly over 20 dB over the frequency band from 70 MHz to 2 GHz. Since the through-type capacitor used in the present invention is directly mounted to the enclosure, there is no lead wire as compared with the conventional aluminum capacitor, and thus does not generate a series resonance phenomenon caused by the inductance component of the lead. The toroidal core 23 and the ferrite core 24 of the last stage increase the input impedance of the load to be connected to the output of the filter and block the influence of the induced voltage input to the load. At this time, parallel resonance occurs due to the winding capacity of the toroidal core 23, and the ferrite core 24 serves to eliminate the parallel resonance point on the power line by canceling the parallel resonance.

As described above, the present invention provides a flat attenuation characteristic of more than 20 dB over a broadband from 70 MHz to 2 GHz for the unwanted electromagnetic wave induced in the power line input to the device, and provides an effect of not generating a series / parallel resonance point. .

Claims (3)

A filter that removes unnecessary electromagnetic waves induced in a two-phase AC power source and outputs it to a load, and transients that attenuate electrostatic voltage, surge voltage, and continuous / discontinuous transient voltages induced in the input power source and output them to the next stage A through-type capacitor unit mounted directly to the voltage protection unit and the enclosure and outputting attenuated undesired electromagnetic waves from 70 MHz to 2 GHz that are induced in the power supply in which the transient voltage is attenuated by 20 dB or more to the next stage; A core part having a troroidal core and a ferrite core that cancels the parallel resonance phenomenon generated from the troidal core to output a power attenuated by the undesired electromagnetic wave to a load and to increase an input impedance of the load; And an enclosure that shields the components with external electromagnetic waves and is grounded. 2. The transient voltage protection unit of claim 1, wherein the transient voltage protection unit includes three varistors connected between the first phase power line and the second phase power source, between the first phase power line and the enclosure, and between the second phase power line and the enclosure, respectively. Wide band EMC filter. The broadband EMC filter of claim 1, wherein the through capacitor comprises two through capacitors connected between the first phase power line and the enclosure and between the second phase power source and the enclosure.