KR101266475B1 - cable fault diagnostic system and method - Google Patents

Abstract

A cable fault diagnosis system and method are provided. Cable fault diagnosis system according to an embodiment of the present invention, the signal generator for generating a continuous reference signal of a predetermined waveform; A first coupler for applying the reference signal to a cable; A second coupler for obtaining a reflected signal formed by the reference signal being reflected in the cable; A bit frequency detector detecting a beat frequency from a signal in which the reference signal and the reflected signal overlap; And a defect diagnosis unit for diagnosing a defect of the cable based on the bit frequency.

Description

Cable fault diagnostic system and method

The present invention relates to a system and method for diagnosing a cable defect, and more particularly, using a frequency modulation continuous waveform (FMCW) signal, which is a continuous signal, to prevent a degradation in resolution due to signal overlap and to improve SNR according to continuous signal application. The present invention relates to a cable fault diagnosis system and method having a signal-to-noise ratio.

Cable diagnostics are aimed at cable defects that may cause an accident. The cable condition including the main insulation layer is used as the diagnostic scope to assess the condition of the cables. As the main cause of several aircraft crash accidents since the mid-90s was found to be the problem of electrical wiring, the importance of precision wiring fault diagnosis technology and the ripple effect on the public began to be recognized.

To this end, researches on reflected wave measurement methods for diagnosing wiring defects by analyzing a signal returned after applying a constant signal to a conductive wire for diagnosing wiring defects have been actively conducted for several years. Reflective wave measurement methods are classified into time domain reflectometry (TDR), frequency domain reflectometry (FDR), and time-frequency domain reflectometry.

However, the reflected wave measurement method for diagnosing a conventional cable applies a reference signal in the form of a pulse, and when a cable defect exists in a short distance at a measurement point, the resolution reflected by the reference signal and the signal reflected at the defect point is reduced. There is a problem.

In addition, the conventional reflected wave measuring method has narrowed the width of the pulse to increase the resolution, but when the width of the pulse decreases, the energy of the pulse decreases, making it difficult to detect the reflected wave.

The present invention is to solve the above problems, by applying a continuous reference signal to the cable cable fault diagnosis system for diagnosing the exact position of the fault of the cable even without a decrease in resolution even if there is a fault in the cable near the measurement point and To provide a way.

In addition, there is no need to reduce the width of the pulse by applying a continuous reference signal to the cable to reduce the energy of the reference signal to provide a cable fault diagnosis system and method with improved fault diagnosis capability of the cable.

Problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Cable fault diagnosis system according to an embodiment of the present invention for achieving the above object, Signal generation unit for generating a continuous reference signal of a predetermined waveform; A first coupler for applying the reference signal to a cable; A second coupler for obtaining a reflected signal formed by the reference signal being reflected in the cable; A bit frequency detector detecting a beat frequency from a signal in which the reference signal and the reflected signal overlap; And a defect diagnosis unit for diagnosing a defect of the cable based on the bit frequency.

According to another aspect of the present invention, there is provided a cable fault diagnosis method comprising: (a) applying a reference signal in the form of a frequency modulated continuous wave (FMCW) signal to a cable; (b) acquiring a reflected signal of the reference signal reflected at a defect point of the cable; (c) detecting a beat frequency from a signal in which the reference signal and the reflected signal overlap; And (d) diagnosing a defect point of the cable using the bit frequency.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention, the continuous reference signal is applied to the cable, so that a defect point of the cable at a short distance can be accurately diagnosed at the point of application of the cable to which the reference signal is applied.

In addition, since the FMCW signal is applied to the cable rather than the pulse signal, the energy of the signal applied to the cable is not reduced, so that the fault diagnosis capability of the cable can be significantly improved.

1 is a block diagram of a cable fault diagnosis system according to an embodiment of the present invention.
2 is a diagram illustrating a result of bit frequencies according to reference signals and reflected signals.
3 is a flow chart of a cable fault diagnosis method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

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

1 is a block diagram of a cable diagnostic system according to an embodiment of the present invention.

The cable fault diagnosis system 100 may include a signal generator 110 for generating a continuous reference signal of a predetermined waveform, a first coupler 120 for applying a reference signal to the cable 10, and a reference signal for the cable ( 10) a second coupler 130 for acquiring a reflection signal formed by being reflected within the bit frequency, a bit frequency detection unit 150 for detecting a beat frequency from a signal in which the reference signal and the reflection signal overlap, and a bit frequency And a defect diagnosis unit 160 for diagnosing a defect of the cable 10 by using the same.

In addition, the cable fault diagnosis system 100 includes a signal generator 110, a first coupler 120, a second coupler 130, a bit frequency detector 150, a fault diagnosis unit 160, and the second. The apparatus may further include a signal acquisition unit 140 that provides the reflected signal acquired from the coupler 130 to the bit frequency detector 150.

Here, the signal generator 110 may generate a frequency modulated continuous wave (FMCW) signal and apply it as a reference signal to the cable 10 through the first coupler 120. That is, the continuous reference signal of the predetermined waveform generated by the signal generator 110 may be used as the FMCW signal. Thus, the FMCW signal may be represented as a continuous signal having a certain period, and the frequency increases linearly and decreases linearly. In general, the FMCW signal is widely used for radar that detects a distance to a target using electromagnetic waves.

The signal generated by the signal generator 110 is applied as a reference signal to the cable 10 through the first coupler 120. In general, a coupler is connected between a device for applying a signal to the cable and the cable 10, and often has a capacitor. However, in this case, since there is a problem of contacting the conductor portion of the cable 10, it is necessary to introduce a non-contact coupler that does not require contact with the conductor portion of the cable.

Thus, an inductive coupler having an inductor is introduced into the first coupler 120. The reference signal generated by the signal generator 110 is applied to the cable 10 through the inductive coupler.

The reference signal applied to the cable 10 is reflected at the defective point of the cable 10. If there is a fault in the cable, the impedance of the cable 10 is not constant so that some or all of the reference signal is reflected at the point where the impedance is inconsistent, thereby generating a reflected signal. In FIG. 1, the reference signal is reflected and returned where the short of the cable 10 is.

When there is a fault in the cable, the second coupler 130 acquires a reflected signal that is reflected back at the point where the impedance is not consistent because the impedance of the cable 10 is not constant. In order to solve the problem that the second coupler 130 also needs to be connected to the conductor portion of the cable 10 like the first coupler 110, it is necessary to introduce a non-contact coupler that does not require contact with the conductor portion of the cable. have.

Therefore, an inductive coupler having an inductor is introduced into the second coupler 130. Through the second coupler 130 which is an inductive coupler, a reflected signal reflected at a point where the impedance of the cable 10 is different is acquired.

Thus, when both the first and second couplers 120 and 130 are configured as inductive couplers, it is possible to implement the cable fault diagnosis system 100 without directly contacting the conductor portion of the cable. Since the reference signal is applied to the cable 10 through the first coupler 120, the reference signal generated from the signal generator 110 is applied to the cable 10 while the power is supplied to the cable 10. It is possible to. Thus, it is possible to diagnose a defect of the cable 10 in the state where a voltage is applied to the cable 10.

When a continuous signal, for example an FMCW signal, is applied to the cable as a reference signal so that the impedance of the cable 10 is reflected at a different defect point, resulting in a reflected signal, the reference signal and the reflection at the defect point of the cable 10 The signals overlap. The superimposed signal has a beat frequency due to the time difference between the reference signal and the reflected signal. The bit frequency detector 150 detects a bit frequency generated by the overlap of the reference signal and the reflected signal. In this case, the cable fault diagnosis system 10 may be implemented such that the signal acquisition unit 140 acquires not only the reflected signal but also a bit signal that is a superimposed signal of the reference signal and the reflected signal.

The bit frequency can be expressed as a function of the distance to the measurement point and the defect point of the cable 10 and the frequency sweep rate. Thus, the defect diagnosis unit 160 can diagnose the defect of the cable using the bit frequency.

The bit frequency is expressed by Equation 1 below.

Where fb is the bit frequency, R is the distance, Δt is the sweep time, Δf is the frequency bandwidth of the sweep signal, and c is the speed of light.

Therefore, the frequency bandwidth and the sweep time of the reference signal can be known, and the bit frequency can be measured by the bit frequency detector 150 so that the point from the application point where the reference signal is applied to the defective point of the defect in the cable 10 can be obtained. The distance can be calculated. That is, the defect diagnosis unit 160 may calculate and estimate the distance from the application point to which the reference signal is applied to the defect point at which the defect of the cable 10 exists using the equation (1).

It can be seen from Equation 1 that the bit frequency increases as the sweep frequency bandwidth is wider or the sweep time is shorter. If the frequency sweep is not linear at this time, the beat frequency will vary with time. In addition, if the cable 10 is close to the first coupler 120, the delay time is shortened, so that the bit frequency is low, while if the distance is far, the bit frequency is high.

Next, a specific embodiment of diagnosing a defect of the cable 10 will be described with reference to FIG. 2.

2 is a diagram illustrating a result of bit frequencies according to reference signals and reflected signals.

2 shows the reference signal applied to the cable 10 and the reflected signal reflected from the defect of the cable 10. Here, the reference signal is indicated by a solid line and the reflected signal is indicated by a dotted line. At this time, there is a time delay between the reference signal and the reflected signal, and this is Δt. In addition, the bottom graph of FIG. 2 shows the beat frequency of the cable 10 which is a stationary target.

In Figure 2, the modulation frequency fm can be expressed by the following equation (2).

In addition, in FIG. 2, the rate of frequency change may be obtained by Equation 3 below.

Where Δf is the peak frequency deviation.

In addition, since the bit frequency fb is generated during the time delay Δt in FIG. 2, the bit frequency is expressed by the following equation (4).

Here, R is the distance between the initial application point of the reference signal applied to the cable 10 and the defect point which is the first point reflected by the defect of the cable 10.

Accordingly, in FIG. 2, the bit frequency is represented by the following equation (5) from the above equations (3) and (4).

Therefore, when the waveform of FIG. 2 is applied to the cable 10 as a reference signal to measure the bit frequency, the defect point of the cable can be known. In this case, when Equation 2 is substituted into Equation 5, Equation 5 is identical to Equation 1 in the result.

Since the reference signal of FIG. 2 linearly increases and decreases at a predetermined period, the bit frequency decreases and then increases again at the inflection point. This is shown in the bottom graph of FIG. Here, the bit frequency is kept constant by the linearity of the reference signal and then decreases linearly at the inflection point of the reference signal, and the bit frequency becomes zero at the point where the reference signal and the reflected signal intersect. It can then be seen that the bit frequency increases linearly again and remains constant again at the point of variation of the reflected signal.

Until now, each component of FIG. 1 may refer to software, or hardware such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, the components are not limited to software or hardware, and may be configured to be in an addressable storage medium and configured to execute one or more processors. The functions provided in the above components may be implemented by more detailed components, or may be implemented as one component that performs a specific function by combining a plurality of components.

Next, a cable defect diagnosis method according to an embodiment of the present invention will be described with reference to FIG. 3.

3 is a flow chart of a cable fault diagnosis method according to an embodiment of the present invention.

First, a signal in the form of an FMCW signal is generated (S310), and the FMCW signal is applied to the cable 10 as a reference signal (S320). Here, the FMCW signal is preferably a continuous signal in which the frequency increases linearly and decreases linearly at a predetermined period. When the FMCW signal is applied to the cable 10, the FMCW signal may be applied to the cable 10 as a reference signal using an inductive coupler. This is for applying the FMCW signal to the cable 10 in a non-contact manner without directly connecting to the conductor portion of the cable 10 using an inductive coupler.

Next, a reflection signal of the reference signal reflected at the defect point of the cable 10 is obtained (S330). In this case, the method may further include acquiring a reflected signal reflected at a defect point of the cable 10 using an inductive coupler. This is to obtain the reflected signal of the FMCW signal reflected at the defect point of the cable 10 in a non-contact manner, without directly connecting to the conductor portion of the cable 10 using an inductive coupler, like the reference signal.

Next, a beat frequency is detected from a signal in which the reference signal and the reflected signal overlap (S340). The beat frequency can be detected simply using a measuring device.

Finally, the defect point of the cable 10 is diagnosed using the measured and detected bit frequency (S350). At this time, the defect point of the cable 10 can be calculated using the above equation (1). In particular, when the signal applied to the cable 10 is a continuous FMCW signal in which the frequency increases linearly and decreases linearly at regular intervals, it is the same shape as the top graph of FIG. Can be.

The present invention has advantages in terms of short-range defect measurement resolution and signal-to-noise ratio (SNR) of the cable 10 by supplementing the disadvantages of the reflected wave measurement method using a conventional pulse as a reference signal, Even in the live state, the defect of the cable 10 can be diagnosed. This allows a wide range of applications in power plant diagnostics.

On the other hand, the cable diagnostic method of the present invention can be implemented as a single module by software and hardware, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, using a computer-readable recording medium Can be implemented in a general-purpose computer for operating the program. The computer-readable recording medium is implemented in the form of a carrier wave such as a ROM, a floppy disk, a magnetic medium such as a hard disk, an optical medium such as a CD or a DVD, and a transmission through the Internet. In addition, the computer-readable recording medium may be distributed to a network-connected computer system so that computer-readable codes may be stored and executed in a distributed manner.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

110: signal generator 120: first coupler
130: second coupler 140: signal acquisition unit
150: bit frequency detection unit 160: defect diagnosis unit

Claims (11)

A signal generator for generating a continuous reference signal of a preset waveform;
A first coupler for applying the reference signal to a cable;
A second coupler for obtaining a reflected signal formed by the reference signal being reflected in the cable;
A bit frequency detector detecting a beat frequency from a signal in which the reference signal and the reflected signal overlap; And
A defect diagnosis unit for diagnosing a defect of the cable based on the bit frequency,
And the first and second couplers are inductive couplers having an inductor. The method of claim 1,
The reference signal is a cable fault diagnosis system, FMCW (Frequency Modulated Continuous Waveform) signal. delete The method of claim 1,
And the first coupler is configured to apply the reference signal generated from the signal generator to the cable while power is supplied to the cable. The method of claim 1,
And the first and second couplers are arranged so as not to be in direct contact with the conductor portion in the cable. The method of claim 1,
The defect diagnosis unit,

Using to estimate the distance from the application point to which the reference signal is applied to the defect point of the defect of the cable,
Wherein fb is the bit frequency, R is the distance, Δt is the sweep time, Δf is the frequency bandwidth of the sweep signal, and c is the speed of light. The method of claim 1,
And a signal acquisition unit for providing the reflected signal acquired by the second coupler to the bit frequency detector. (a) generating a Frequency Modulated Continuous Waveform (FMCW) signal and applying the generated FMCW signal to a cable as a reference signal using an inductive coupler;
(b) acquiring a reflected signal of the reference signal reflected at a defect point of the cable;
(c) detecting a beat frequency from a signal in which the reference signal and the reflected signal overlap; And
(d) diagnosing a defect point of the cable using the bit frequency. The method of claim 8,
The FMCW signal is a cable fault diagnosis method, which is a continuous signal in which the frequency increases linearly and decreases linearly at regular intervals. delete The method of claim 8,
The step (b) includes the step of acquiring the reflected signal reflected from the cable using an inductive coupler.

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