TWI684325B - Circuit capable of suppressing magnetic saturation of high frequency current transformer - Google Patents

Abstract

The present invention relates to a circuit capable of suppressing magnetic saturation of a high frequency current transformer. It comprises a high frequency current transformer including a primary side and a secondary side relative to the primary side, wherein the primary side receives an electrical signal and the secondary side is disposed with a secondary winding; a high-pass filter electrically connected to the secondary winding of the high frequency current transformer; a low-pass filter electrically connected to the secondary winding of the high frequency current transformer and the high-pass filter; and an inverse current winding electrically connected to the low-pass filter to eliminate the low frequency magnetic flux.

Description

Circuit capable of suppressing magnetic saturation of high-frequency current transformer

The present invention relates to a circuit that can suppress the magnetic saturation of a high-frequency current transformer, especially refers to a circuit that can avoid magnetic saturation of the iron core. The present invention uses a filter as a shunt to guide the current loop, and through an additional reverse The winding generates reverse magnetic flux to eliminate low-frequency magnetic flux, so that the iron core can withstand large currents and avoid magnetic saturation.

According to the existing monitoring equipment for partial discharge of power equipment, a high-frequency current transformer is usually used to hook the ground wire of the power equipment. After the partial discharge signal is measured, data analysis is performed through the partial discharge detector to generate a discharge pattern. Type to determine the phase, type of discharge and the amount of discharge to control the operating status of power equipment.

Republic of China Patent Announcement No. TW I303316 "Simple partial discharge detector using high-frequency current transformer", which includes high-frequency current transformer, filter, amplifier, comparator, pulse width modulation circuit and single chip; The pulse wave current is received by the high-frequency current transformer, and the best discharge waveform can be obtained after passing through the filter and the amplifier, and then the square wave is generated by the comparator and the pulse width modulation circuit and sent to the single chip. Counters and timers to record the number and time of discharge, respectively, to facilitate detection and analysis of discharge type and cause identification.

In addition, the Republic of China Patent Announcement No. TW I598601 "Partial Discharge Detection Method, UHF Antenna, Partial Discharge Detection System, and Signal Processing Unit" uses UHF antenna to sense electrical equipment and produce a spectrum result Then, according to the spectrum result, it can be judged whether the electrical equipment has a partial discharge. The patent in the previous case can also down-convert the spectrum result to produce a frequency-down spectrum result. When the frequency-down spectrum result meets a specific condition, according to the frequency-down frequency Spectrum results to determine whether partial discharge occurs in electrical equipment.

However, the internal connection environment of the power equipment in each place is different, and the power supply circuit and the ground line are also different. The discharge signal is often subject to noise interference from the ground or other lines. These noise interference will affect the power. The discharge value during the measurement of equipment, and the ground wire of power equipment often have large currents of DC and low frequency, which makes the iron core of the measurement instrument particularly easy to reach magnetic saturation, which causes distortion and causes the measurement instrument to fail to measure normally. Secondly, how to provide a measuring instrument capable of reducing noise interference and avoiding magnetic saturation is the direction that the inventor has thought.

Now, in view of the fact that the above-mentioned existing partial discharge measurement equipment still has many deficiencies in actual implementation and use, it is a tireless spirit, and is assisted by its rich professional knowledge and many years of practical experience, and Improve it and research and create the present invention accordingly.

The main purpose of the present invention is to provide a circuit capable of suppressing magnetic saturation of a high-frequency current transformer, which uses a high-pass filter and a low-pass filter to separate signals of different frequencies, and uses a reverse winding to suppress the ground line of the device under test. The generated magnetic flux avoids reaching magnetic saturation, so that the invention can continuously measure the discharge signal of the device under test.

In order to achieve the above-mentioned implementation objective, the present invention provides a circuit capable of suppressing magnetic saturation of a high-frequency current transformer, which includes a high-frequency current transformer, which has a primary side and a secondary side opposite to the primary side. The primary side receives An electrical signal, and the secondary side is provided with a secondary winding; a high-pass filter, which is electrically connected to the secondary winding of the high-frequency current transformer; a low-pass filter, which is electrically connected to the high-frequency specific current The secondary winding of the device and the high-pass filter; and a reverse current winding are electrically connected to the low-pass filter to eliminate low-frequency magnetic flux.

In an embodiment of the invention, the high-pass filter is electrically connected to an oscilloscope.

In an embodiment of the invention, the high-pass filter is a first capacitor and a first inductor connected in series with the first capacitor.

In an embodiment of the invention, the low-pass filter is a second capacitor and a second inductor connected in series with the second capacitor.

In one embodiment of the present invention, the secondary winding and the reverse current winding are connected in parallel.

In an embodiment of the invention, the electrical signal is a current signal of the ground line of the device under test.

In one embodiment of the present invention, there is an iron core between the primary side and the secondary side of the high frequency current transformer.

The purpose of the present invention and its structural and functional advantages will be explained based on the structure shown in the following drawings and in conjunction with specific embodiments, so that the reviewing committee can have a more in-depth and specific understanding of the present invention.

Please refer to the first figure, a circuit for suppressing magnetic saturation of a high-frequency current transformer according to the present invention includes a high-frequency current transformer (1), which has a primary side (11) and a primary side (11) ) The secondary side (12) and an iron core (13) arranged between the primary side (11) and the secondary side (12), the primary side (11) receives an electrical signal, which is the ground of the device under test The current signal of the line (2), and the secondary side (12) is provided with a secondary winding (14); a high-pass filter (3) is electrically connected to the secondary winding of the high-frequency current transformer (1) (14) It has a first capacitor (31) and a first inductor (32) connected in series with the first capacitor (31); a low-pass filter (4) is electrically connected to the high-frequency current transformer (1) ) Secondary winding (14) and high-pass filter (3), which has a second capacitor (41) and a second inductor (42) in series with a second capacitor (41); and a reverse current winding (5 ), which is electrically connected to the low-pass filter (4) and connected in parallel with the secondary winding (14) to eliminate low-frequency magnetic flux.

Among them, the high-pass filter (3) is electrically connected to an oscilloscope (6), and the electrical signal of the measured discharge of the ground wire (2) can be displayed on the oscilloscope (6). Test the running status of the equipment.

In addition, through the following specific embodiments, the scope of the present invention can be further proved to be practical, but it is not intended to limit the scope of the present invention in any form.

Please continue to refer to the first figure. The circuit for suppressing magnetic saturation of a high-frequency current transformer of the present invention mainly eliminates the low-frequency current caused by the ground wire (2) of the device under test by the reverse current winding (5) The magnetic flux causes high frequency signals to be left to reduce the possibility of magnetic saturation of the iron core (13).

In actual use, first hook the high-frequency current transformer (1) to the ground line (2) of the device under test. The equivalent circuit formed by it should be as shown in the second figure. ) On the primary side (11), for example, a winding can be connected to a current source to represent the ground line (2) of the device under test; the high-frequency current transformer (1) hooked to the ground line (2) of the device under test The side (11) will receive the electrical signal of the ground wire (2), that is, the discharge signal of the ground wire (2), and then the secondary winding (14) will generate the corresponding response signal through the iron core (13). , The response signal will pass through the high-pass filter (3) and the low-pass filter (4), and the response signal is divided into high-frequency and low-frequency signals according to the frequency, so that the high-frequency response signal can pass the high-pass filter (3) The noise interference is filtered out, and the low-frequency response signal will be guided through the low-pass filter (4) and transmitted to the part of the reverse current winding (5), so that the reverse current winding (5) will produce a reverse Magnetic flux current, to eliminate the magnetic flux caused by the low-frequency response signal, to suppress the possibility of magnetic saturation. Furthermore, when the current discharged by the ground wire (2) is higher, the reverse current winding (5) will produce more Large reverse flux current.

In this way, the low-frequency response signal will be eliminated in the circuit, and only the high-frequency response signal is left, and the high-frequency response signal is transmitted to the oscilloscope (6). The response signal is presented as a waveform to provide monitoring, The invention can control the running status of the device to be tested by sensing the discharge signal of the device to be tested.

It can be seen from the above implementation description that the present invention has the following advantages compared with the prior art:

1. The circuit capable of suppressing the magnetic saturation of the high-frequency current transformer of the present invention has a high-pass filter and a low-pass filter, which can distinguish the sensed discharge signal into high-frequency and low-frequency signals, and target two different frequencies. The signal is processed to reduce the negative effects caused by the low-frequency signal, and the noise interference of the high-frequency signal is effectively suppressed within a certain range.

2. The circuit capable of suppressing the magnetic saturation of the high-frequency current transformer of the present invention has a reverse current winding, which can process the low-frequency signal directed to the low-pass filter, which eliminates the magnetic flux generated by the low-frequency signal and avoids the magnetic saturation of the iron core. The situation occurs, so that when the invention measures the discharge signal of the device under test, the iron core can withstand a large current and continue to work, and it is not easy to produce distortion in the signal measurement.

In summary, the circuit of the present invention that can suppress the magnetic saturation of the high-frequency current transformer can indeed achieve the expected use effect by the embodiments disclosed above, and the present invention has not been disclosed before the application. Fully comply with the provisions and requirements of the Patent Law. I filed an application for a patent for invention in accordance with the law, pleaded for the review, and granted the patent.

However, the illustrations and descriptions disclosed above are only preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention; those who are familiar with this skill, according to the characteristic scope of the present invention, do other things Equivalent changes or modifications should be regarded as not departing from the design scope of the present invention.

(1)‧‧‧High-frequency current regulator (11)‧‧‧primary side

(12)‧‧‧Secondary side (13)‧‧‧Iron core

(14)‧‧‧Secondary winding (2)‧‧‧Ground wire

(3)‧‧‧High-pass filter (31)‧‧‧First capacitor

(32)‧‧‧First inductance (4)‧‧‧Low-pass filter

(41)‧‧‧Second capacitor (42)‧‧‧Second inductor

(5)‧‧‧Reverse current winding (6)‧‧‧oscilloscope

Figure 1: Schematic diagram of the preferred embodiment of the present invention.

Figure 2: Part of the circuit diagram of the preferred embodiment of the present invention.

(1)‧‧‧High-frequency current regulator

(13)‧‧‧Iron core

(14)‧‧‧Secondary winding

(2)‧‧‧Ground wire

(3)‧‧‧High-pass filter

(4)‧‧‧Low-pass filter

(5)‧‧‧Reverse current winding

(6)‧‧‧oscilloscope

Claims (7)

A circuit capable of suppressing magnetic saturation of a high-frequency current transformer includes: a high-frequency current transformer having a primary side and a secondary side opposite to the primary side, the primary side receiving an electrical signal , And the secondary side is provided with a secondary winding; a high-pass filter, which is electrically connected to the secondary winding of the high-frequency current transformer; a low-pass filter, which is electrically connected to the high-frequency current transformer The secondary winding and the high-pass filter; and a reverse current winding are electrically connected to the low-pass filter to eliminate low-frequency magnetic flux. The circuit that can suppress the magnetic saturation of the high-frequency current transformer as described in item 1 of the patent application scope, wherein the high-pass filter is electrically connected to an oscilloscope. The circuit capable of suppressing magnetic saturation of a high-frequency current transformer as described in item 1 of the patent application scope, wherein the high-pass filter is a first capacitor and a first inductor connected in series with the first capacitor. As described in Item 1 of the patent application range, a circuit capable of suppressing magnetic saturation of a high-frequency current transformer, wherein the low-pass filter is a second capacitor and a second inductor connected in series with the second capacitor. As described in Item 1 of the patent application range, a circuit that can suppress magnetic saturation of a high-frequency current transformer, in which the secondary winding and the reverse current winding are connected in parallel. The circuit that can suppress the magnetic saturation of the high-frequency current transformer as described in item 1 of the scope of the patent application, wherein the electrical signal is the current signal of the ground line of the device under test. A circuit capable of suppressing magnetic saturation of a high-frequency current transformer as described in item 1 of the scope of the patent application, wherein the high-frequency current transformer has an iron core between the primary side and the secondary side.

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