CN110764027B - Electric connector intermittent fault diagnosis method based on frequency spectrum characteristic change - Google Patents
Electric connector intermittent fault diagnosis method based on frequency spectrum characteristic change Download PDFInfo
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Abstract
The method for diagnosing intermittent faults of the electric connector based on the frequency spectrum characteristic change comprises the steps of loading N repeatable pulses on each connecting line of the electric connector to obtain enough sampling data, carrying out frequency spectrum characteristic analysis on the sampling data, carrying out statistical analysis on energy frequency spectrum characteristics of the N times of data, calculating the difference degree of the energy frequency spectrum characteristics, exceeding a threshold range, judging that intermittent faults are easy to occur, and finally obtaining the probability of the intermittent faults of the electric connector by synthesizing all connecting line test results of the electric connector; the higher the probability of intermittent faults occurring during actual operation, the simpler and more reliable the method than other methods, and the probability of intermittent faults occurring is estimated.
Description
Technical Field
The invention relates to the technical field of fault diagnosis, in particular to an intermittent fault diagnosis method for an electric connector based on frequency spectrum characteristic change.
Background
Intermittent faults are commonly caused in a complex equipment system, and further serious expense burden and safety risk are caused. Intermittent faults are non-permanent faults which can repeatedly appear and disappear automatically without treatment, and have randomness, intermittence and repeatability. In electronic equipment, especially large-scale integrated circuits, intermittent faults of circuits can be caused by insufficient soldering of components, loosening of chip pins and connecting wires and the like caused by poor manufacturing process, irregular use and the like. The frequency of intermittent faults is 10-30 times of that of permanent faults, and the intermittent faults are main reasons for system failure. The intermittent faults of the electric connector are main sources of the intermittent faults, and are difficult to reproduce, test and diagnose. Statistics show that 70% of various system failures are caused by component failures, and 40% of them are caused by electrical connector failures. If 30-60% of electronic faults in an automobile are caused by degradation of an electric connector, statistical analysis on field fault data of a ship finds that the connection type faults account for 26.89% of all faults, and the connection type faults in an integral packaging part are not included yet. It is certain that the proportion of connection-type failures to all failures is higher than 30%.
At present, there are many methods for extracting fault features, such as fast fourier transform, wavelet packet transform, cepstrum, and Wigner distribution, but intermittent faults are difficult to extract due to their randomness and discontinuity. An Intermittent Fault Detection and Isolation System (IFDIS) developed by the United states Universal synthetic can detect the defects and faults of a transmission line, but not Intermittent faults, and an IDF-2000 product of the System sends out signals and detects echo signals after being connected with a device line, and judges whether the faults occur or not by detecting the instantaneous change of the resistance of a unit to be detected; for intermittent faults of intermittent resistance increase and phase coil short circuit of the alternating-current permanent magnet motor, such as Zanardelli, Zaidi and the like, respectively extracting fault characteristics from an original collected signal by utilizing short-time Fourier transform, non-sampling discrete wavelet transform, Wigner-Ville distribution and Choi-Williams distribution, and realizing the judgment of a fault mode by adopting a linear classifier and a k-mean classifier; banerjee proposes a clustering DFD (distribution fault diagnosis) strategy for diagnosing intermittent faults of the sensor nodes; alamuti deduces fault characteristics aiming at arc intermittent faults of a feeder line in a medium-voltage power transmission system based on inherent parameters of the line, and identifies and positions the intermittent faults by measuring voltage and current at a single end, but the method depends on modeling precision; for the ground instantaneous fault and the intermittent fault of the power transmission system, the Cui Tao identifies the instantaneous power direction by Hilbert transform, and provides a fault diagnosis algorithm based on the signal characteristics.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method for diagnosing intermittent faults of an electrical connector based on spectral characteristic changes, so as to solve the problems in the background art.
The technical problem solved by the invention is realized by adopting the following technical scheme:
the method for diagnosing the intermittent faults of the electric connector based on the frequency spectrum characteristic change comprises the following specific steps:
1) selecting a connecting line to be tested of the electric connector, setting a pulse width value tau and an action time T according to the length of the connecting line and judging the energy ratio threshold lambda of the inconsistency of the two frequency spectrumsmax；
2) Generating a pulse signal with the amplitude of 5V and the width of tau through a singlechip, amplifying the pulse signal by a signal processing circuit, and outputting the pulse signal to a to-be-tested connecting line of an electric connector, wherein the other end of the electric connector is connected with actual equipment, and the actual equipment is placed in a simulated working environment;
3) the pulse signal generates a reflection signal through an electric connector port, if the connected actual equipment also generates a load effect, an actual return signal is finally formed, the actual return signal is processed by a signal processing circuit and returns to an ADC port controlled by a singlechip to carry out analog signal sampling, and data acquired by the ADC port comprises information of a normal state, an intermittent fault state and a permanent fault state of the connecting line to be tested;
4) the single chip microcomputer carries out FFT conversion on the data collected by the ADC port in the step 3) to form frequency spectrum characteristics and stores the frequency spectrum characteristics to form 1 group of frequency spectrum characteristic data;
5) under the condition of keeping the pulse width and the action time unchanged, repeating the step 2) to the step 4) for N times on the same path of connecting line to be tested selected in the step 1) to obtain N groups of frequency spectrum characteristic data;
6) comparing the energy spectrum difference degree lambda of any ith group and j group in the N groups of spectrum characteristic data obtained in the step 5) by the singlechipijIf the energy spectrum differs by a degree lambdaijLess than an energy ratio threshold lambdamaxJudging that the system belongs to the same system working state; in N groups of frequency spectrum characteristic data, the data group with the consistent energy frequency spectrum distribution with the largest number is judged to be in a normal working state or a permanent fault working state, and the data group with the small number (possibly 0) is judged to be in an intermittent fault state;
7) calculating the proportion number of the intermittent fault state in the step 6) as the probability of the intermittent fault, thereby obtaining the probability of the intermittent fault on the connecting line to be tested of the electric connector;
8) and selecting other untested connecting lines on the electric connector, repeating the steps 1) to 7), and counting and analyzing the result to obtain the intermittent fault probability of the electric connector after the connecting lines of all the pins or jacks of the electric connector are tested.
In the invention, in the step 1), the pulse width value tau is set to be 10 nanoseconds to 10 microseconds.
In the invention, in the step 2), the action time T of the pulse signal does not exceed 5 seconds.
In the present invention, in step 6), the energy spectrum difference degree λijThe calculation formula of (2) is as follows:
in the formula (1), a and b are the frequency range of interest, EcIs the energy in the frequency band of interest, EciRepresenting the energy of the ith group of frequency bands of interest, AkiRepresents the amplitude of the ith group of kth frequency components when lambdaijWhen the average molecular weight is more than 0.2, the difference is judged to be very significant.
In the present invention, in step 6), the energy ratio threshold λ is setmaxTake 0.2.
Has the advantages that:
1) the invention does not need to research the complex dynamic characteristics of the electric connector, judges the probability of intermittent faults of each connecting wire of the electric connector through single-ended test, and is simple, practical and reliable; the method comprises the steps that only N times of repeatable pulse action signals are loaded on each connecting line of the electric connector, enough sampling data are obtained to carry out spectrum characteristic analysis, the consistency of the spectrum characteristics of the electric connector is statistically analyzed, when the spectrum characteristics are inconsistent, intermittent faults are judged, and the probability of the intermittent faults of the electric connector is judged by synthesizing test results of all the connecting lines of the electric connector;
2) according to the method, the spectrum characteristics of the sampling signals are obtained through an energy spectrum difference degree formula and combined with Fourier transform, the consistency of the energy spectrum characteristics of each frequency band is further compared, if the energy spectrum characteristics exceed a set noise energy ratio threshold value, intermittent faults are considered to occur, the more the state occurs, the higher the possibility of intermittent faults is in the actual working process, compared with other methods, the method is simple and reliable, and the probability of intermittent faults is estimated.
Drawings
Fig. 1 is a schematic diagram of the electrical connector according to the preferred embodiment of the invention.
Fig. 2 is a flow chart of intermittent fault diagnosis in the preferred embodiment of the present invention.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.
Referring to fig. 1-2, the method for diagnosing intermittent faults of an electrical connector based on frequency spectrum characteristic change comprises the following specific steps:
1) selecting one connecting line to be tested of the electric connector, setting a pulse width value tau (set to be 10 nanoseconds-10 microseconds) and action time T (10000 times of pulse width) according to the length of the connecting line and judging the inconsistent energy ratio threshold lambda of two frequency spectrumsmax；
2) Generating a pulse signal with the amplitude of 5V and the width of tau through a singlechip (or FPGA), amplifying the pulse signal by a signal processing circuit, and outputting the pulse signal to a to-be-tested connecting line of an electric connector, wherein the other end of the electric connector is connected with actual equipment, the actual equipment is placed in a simulated working environment (such as vibration and temperature conditions), and the action time T of the pulse signal is not more than 5 seconds;
3) the pulse signal will produce the reflected signal through the electric connector port, if the actual apparatus connected also produces the load effect, form the actual return signal finally, process by the signal processing circuit, return to ADC port that the one-chip computer (or FPGA) controls and sample the analog signal, data that ADC port gathers include the normal condition that should test the line to be connected exists, intermittent fault state and permanent fault state information, because the pulse signal width tau is limited, the reaction time T is short, can think it is in a state only;
4) the single chip microcomputer (or FPGA) carries out FFT transformation on the data collected in the step 3) to form and store frequency spectrum characteristics to form 1 group of frequency spectrum characteristic data;
5) under the condition that the pulse width and the action time are kept unchanged, repeating the step 2) to the step 4) for N times by using the same path of connecting line to be tested selected in the step 1) to obtain N groups of frequency spectrum characteristic data, and paying attention to the simulated working environment conditions such as vibration, temperature and the like, wherein the simulated working environment conditions are reflected in the N times of tests;
6) comparing the energy spectrum difference degree lambda of any ith group and j group in the N groups of frequency spectrum characteristic data obtained in the step 5) by the singlechip (or FPGA)ijIf the energy spectrum differs by a degree lambdaijLess than an energy ratio threshold lambdamaxJudging that the system belongs to the same system working state; in N groups of spectrum characteristic data, the data groups with consistent energy spectrum distribution with the largest number should belong to a normal working state or a permanent fault working state, and the data groups with the small number (possibly 0) are judged to have an intermittent fault state;
the degree of difference λ of the energy spectrumijThe calculation formula of (2) is as follows:
in the formula (1), a and b are the frequency range of interest, EcIs the energy in the frequency band of interest, EciRepresenting the energy of the ith group of frequency bands of interest, AkiRepresents the amplitude of the ith group of kth frequency components when lambdaijWhen the difference is more than 0.2, the difference is judged to be very obvious, and lambda ismaxGenerally taking 0.2;
when intermittent faults occur, the full-frequency-band spectrum energy is not always obviously inconsistent, only a certain frequency band has obvious change, in the actual comparison, the whole frequency band is divided into M bands (generally not less than 20), and the lambda of each frequency band is obtainedijFinally, the maximum value lambda in M frequency bands is selectedijMThe energy spectrum difference degree of the ith and the j two groups of data is taken as the difference degree of the energy spectrum of the ith and the j two groups of data;
7) calculating the proportion number of the intermittent fault state in the step 6) as the probability of the intermittent fault, thereby obtaining the probability of the intermittent fault on the connecting line to be tested of the electric connector;
8) and selecting other untested connecting lines on the electric connector, and repeating the steps 1) to 7), and counting and analyzing the result to obtain the condition that the electric connector has intermittent faults after the connecting lines of all pins or jacks of the electric connector are tested.
Claims (5)
1. The method for diagnosing the intermittent faults of the electric connector based on the frequency spectrum characteristic change is characterized by comprising the following specific steps of:
1) selecting a connecting line to be tested of the electric connector, setting a pulse width value tau and an action time T according to the length of the connecting line and judging the energy ratio threshold lambda of the inconsistency of the two frequency spectrumsmax；
2) Generating a pulse signal with the amplitude of 5V and the width of tau through a singlechip, amplifying the pulse signal by a signal processing circuit, and outputting the pulse signal to a to-be-tested connecting line of an electric connector, wherein the other end of the electric connector is connected with actual equipment, and the actual equipment is placed in a simulated working environment;
3) the pulse signal generates a reflection signal through an electric connector port, if the connected actual equipment also generates a load effect, an actual return signal is finally formed, the actual return signal is processed by a signal processing circuit and returns to an ADC port controlled by a singlechip to carry out analog signal sampling, and data acquired by the ADC port comprises information of a normal state, an intermittent fault state and a permanent fault state of the connecting line to be tested;
4) the single chip microcomputer carries out FFT conversion on the data collected by the ADC port in the step 3) to form frequency spectrum characteristics and stores the frequency spectrum characteristics to form 1 group of frequency spectrum characteristic data;
5) under the condition of keeping the pulse width and the action time unchanged, repeating the step 2) to the step 4) for N times on the same path of connecting line to be tested selected in the step 1) to obtain N groups of frequency spectrum characteristic data;
6) comparing the energy spectrum difference degree lambda of any ith group and j group in the N groups of spectrum characteristic data obtained in the step 5) by the singlechipijIf the energy spectrum differs by a degree lambdaijLess than an energy ratio threshold lambdamaxJudging that the system belongs to the same system working state; in N groups of frequency spectrum characteristic data, the number of data groups with consistent energy frequency spectrum distribution is determined as a normal working state or a permanent fault working state at most, and the number is determined as an intermittent fault state when less;
7) calculating the proportion number of the intermittent fault state in the step 6) as the probability of the intermittent fault, thereby obtaining the probability of the intermittent fault on the connecting line to be tested of the electric connector;
8) and selecting other untested connecting lines on the electric connector, repeating the steps 1) to 7), and counting and analyzing the result to obtain the intermittent fault probability of the electric connector after the connecting lines of all the pins or jacks of the electric connector are tested.
2. The method for diagnosing intermittent faults of an electric connector based on spectral characteristic change according to claim 1, wherein in the step 1), the pulse width value tau is set to be 10 nanoseconds to 10 microseconds.
3. The method for diagnosing intermittent faults of an electric connector based on spectral characteristic change of claim 1, wherein in the step 2), the action time T of the pulse signal is not more than 5 seconds.
4. The method for diagnosing intermittent faults of electric connector based on spectral characteristic change according to claim 1, wherein in step 6), the energy spectrum difference degree lambda isijThe calculation formula of (2) is as follows:
in the formula (1), a and b are the frequency range of interest, EcIs the energy in the frequency band of interest, EciRepresenting the energy of the ith group of frequency bands of interest, AkiRepresents the amplitude of the ith group of kth frequency components when lambdaijWhen the average molecular weight is more than 0.2, the difference is judged to be very significant.
5. The method as claimed in claim 1, wherein in step 6), the energy ratio threshold λ is setmaxTake 0.2.
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