A fault diagnosis method and system for a high-power energy storage projection welding machine

Abstract

The application relates to the technical field of projection welding machine fault diagnosis, and discloses a high-power energy storage projection welding machine fault diagnosis method and system, which comprises the following steps: acquiring an initial contact resistance and a reactance value; calling a standard current rising change characteristic from an inductance parameter grading interval; collecting a discharge current time sequence, and obtaining an actual current rising change characteristic according to the discharge current time sequence; correcting and compensating the actual current rising change characteristic, and then comparing the actual current rising change characteristic with the standard current rising change characteristic to calculate a characteristic deviation value; and determining the performance attenuation state of a switching element according to the determination relationship between the characteristic deviation value and different grade threshold values. Through the design of the initial contact resistance, the reactance value, the grading matching standard current characteristic, the actual waveform correction compensation and the characteristic deviation grading determination, the precision and stability of the performance attenuation determination of the switching element of the high-power energy storage projection welding machine are ensured, and the reliability of equipment fault diagnosis prediction and operation and maintenance control is improved.

Description

Technical Field

[0001] This application relates to the field of projection welding machine fault diagnosis technology, and more specifically, to a fault diagnosis method and system for a high-power energy storage projection welding machine. Background Technology

[0002] High-power energy storage projection welding machines are widely used in modern manufacturing, primarily for projection welding of high-strength steel, hot-formed steel, and non-ferrous metals in automotive bodies and hardware parts. The equipment utilizes the principle of instantaneous discharge from a capacitor, achieving rapid fusion of small-area weld points by precisely controlling the pre-pressure, discharge, forging timing, and charging voltage. The welding machine is equipped with a comprehensive electrical control system and a human-machine interface, supporting multiple welding parameter settings and real-time monitoring, and includes standardized maintenance and troubleshooting procedures. Stable operation relies on precise matching of parameters such as welding current, capacitor voltage, and cooling status, as well as the proper functioning of core components such as the thyristor, energy storage capacitor, and transformer.

[0003] In routine production, operators set welding process parameters according to production needs, and the equipment completes the entire process of charging, energy storage, discharging, and welding according to a predetermined sequence. During production, the sensor module collects operating data such as welding current, capacitor voltage, and circuit conditions in real time, and uploads it to the control system for storage and display. Maintenance personnel conduct daily inspections according to procedures. If obvious faults such as no discharge, poor weld joints, or abnormal parameters occur, they can only refer to the troubleshooting manual to disconnect the power for testing, perform manual measurements, locate the fault based on maintenance experience, and replace the parts. The entire process relies on post-incident handling and experience-based judgment.

[0004] Traditional fault diagnosis methods rely on obvious equipment anomalies as triggers, assuming a sudden shift in component performance from normal to failure, requiring only manual identification afterward. This approach is only suitable for ideal scenarios with stable operating conditions, constant environments, and slow aging, and is unsuitable for high-load continuous production environments in workshops. Equipment operates under high current and high-frequency switching conditions for extended periods, compounded by external interference such as power grid fluctuations, temperature and humidity changes, and heat dissipation fluctuations. Core components like discharge thyristors and energy storage capacitors experience slow performance degradation and gradual parameter drift, rather than sudden, instantaneous failures. Subtle changes such as gradual changes in initial circuit contact resistance and shifts in inductive reactance parameters do not immediately cause equipment shutdown, but gradually lead to unstable welding energy and poor solder joint consistency. These early signs of degradation are difficult to identify through manual inspection.

[0005] Significant limitations exist in industrial applications. Core power electronic components are affected by aging, inrush current, and temperature drift, resulting in performance degradation without a uniform pattern and significant individual differences. Traditional troubleshooting relies excessively on human experience, leading to cumbersome procedures, inaccurate location, and misdiagnosis or omission. When multiple machines operate in parallel, fluctuations in individual machine parameters are easily affected by adjacent line loads, making it difficult for manual inspection to distinguish whether anomalies originate from component degradation or external operating conditions. Furthermore, traditional methods lack early warning capabilities, only allowing reactive shutdowns for repair after weld quality deterioration or equipment failure, severely disrupting production rhythms and causing batch weld quality issues and unplanned downtime losses.

[0006] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this application provides a fault diagnosis method and system for high-power energy storage projection welding machines. This method effectively solves the problem of relying on manual post-incident inspection and difficulty in identifying component performance degradation in advance. By simultaneously identifying the initial contact resistance and inductive reactance of the discharge circuit, combined with standard current characteristic matching, actual current waveform correction and compensation, and graded judgment, the method achieves accurate determination of the performance degradation state of power electronic switching components. This enables early fault warning and quantitative assessment of degradation trends, helping to ensure stable equipment operation and consistent welding processes.

[0008] In a first aspect, this application provides a fault diagnosis method for a high-power energy storage projection welding machine, the method comprising: Obtain the initial contact resistance and inductive reactance of the discharge circuit; Based on the inductive reactance value, the standard current rise and change characteristics corresponding to the current circuit inductance state are retrieved from the preset inductance parameter range. The discharge current time series during the discharge circuit conduction process is collected, and the actual current rise and change characteristics of the discharge circuit are obtained based on the discharge current time series. Based on the interference effect of the initial contact resistance on the discharge process, the actual current rise and change characteristics are corrected and compensated, and then the corrected actual current rise and change characteristics are compared with the standard current rise and change characteristics to calculate the characteristic deviation value between the two. The performance degradation state of the power electronic switching element is determined based on the relationship between the characteristic deviation value and preset threshold values ​​of different levels.

[0009] Secondly, this application provides a fault diagnosis system for a high-power energy storage projection welding machine, used to perform the aforementioned fault diagnosis method for a high-power energy storage projection welding machine. The system includes: The data acquisition module is used to acquire the initial contact resistance and inductive reactance of the discharge circuit; The retrieval module is used to retrieve the standard current rise change characteristics corresponding to the current circuit inductance state from a preset inductance parameter range based on the inductive reactance value. The data acquisition and extraction module is used to acquire the discharge current time series during the discharge circuit conduction process, and obtain the actual current rise and change characteristics of the discharge circuit based on the discharge current time series. The compensation and comparison module is used to correct and compensate the actual current rise and change characteristics based on the interference effect of the initial contact resistance on the discharge process; then, it compares the corrected actual current rise and change characteristics with the standard current rise and change characteristics to calculate the characteristic deviation value between the two. The status determination module is used to determine the performance degradation status of power electronic switching components based on the determination relationship between the characteristic deviation value and preset different level thresholds.

[0010] In summary, this application provides a fault diagnosis method and system for a high-power energy storage projection welding machine. By acquiring the initial contact resistance and inductive reactance of the discharge circuit, and relying on the inductance parameter range matching, it retrieves the standard current rise variation characteristics adapted to the current circuit inductance characteristics, thus overcoming the shortcomings of relying solely on a single parameter to select the reference characteristics, which cannot accurately reflect the actual operating conditions of the circuit. By acquiring the discharge current time series and analyzing and extracting the actual current rise variation characteristics, and then correcting and compensating for the interference deviation caused by the initial contact resistance on the waveform, it avoids the defects of actual characteristic distortion and inaccurate comparison with the reference caused by circuit impedance disturbance. By setting different threshold levels to classify the feature deviation values, it achieves accurate classification of the attenuation state of power electronic switching components, effectively distinguishing between normal aging and potential fault deterioration of components, accurately identifying potential problems such as abnormal discharge and inaccurate response, ensuring the stable and reliable operation of the high-power energy storage projection welding machine, and improving the timeliness and diagnostic accuracy of equipment fault prediction and maintenance. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating a fault diagnosis method for a high-power energy storage projection welding machine provided in an embodiment of this application.

[0012] Figure 2 This is a schematic diagram of a high-power energy storage projection welding machine fault diagnosis system provided in an embodiment of this application.

[0013] Labeling Explanation: 1. Data Acquisition Module; 2. Retrieval Module; 3. Data Collection and Extraction Module; 4. Compensation and Comparison Module; 5. Status Determination Module. Detailed Implementation

[0014] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0015] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0016] refer to Figure 1 This application provides a fault diagnosis method for a high-power energy storage projection welding machine, used for performance diagnosis of energy storage welding equipment. The energy storage welding equipment includes a discharge circuit and a power electronic switching element disposed in the discharge circuit. The method includes the following steps: A1. Obtain the initial contact resistance and inductive reactance of the discharge circuit; A2. Based on the inductive reactance value, retrieve the standard current rise and change characteristics corresponding to the current circuit inductance state from the preset inductance parameter range. A3. Collect the discharge current time series during the discharge circuit conduction process, and obtain the actual current rise and change characteristics of the discharge circuit based on the discharge current time series; A4. Based on the interference effect of the initial contact resistance on the discharge process, the actual current rise and change characteristics are corrected and compensated, and then the corrected actual current rise and change characteristics are compared with the standard current rise and change characteristics to calculate the characteristic deviation value between the two. A5. Based on the relationship between the characteristic deviation value and the preset threshold values ​​of different levels, determine the performance degradation state of the power electronic switching element.

[0017] In this application, the initial contact resistance refers to the resistance value measured before the device discharges and conducts, which is used to evaluate the inherent impedance of the discharge circuit. It can be obtained by methods such as DC volt-ampere testing, AC impedance detection, or pulse response analysis.

[0018] Inductive reactance refers to the inductive reactance of a circuit measured before the equipment is turned on by discharge. It is used to characterize the inductive characteristics of the circuit and can be obtained by frequency scanning identification, phase difference detection or resonance characteristic analysis.

[0019] The preset inductance parameter grading intervals refer to inductance intervals divided according to different inductive reactance values, and each inductance interval pre-stores the current time-domain rise response waveform of the corresponding discharge circuit under ideal operating conditions. This can be achieved through various division methods, such as dividing the inductance parameter grading intervals evenly according to the magnitude of the inductive reactance value; dividing according to the distribution pattern of inductive reactance data during actual equipment operation, densely dividing areas with concentrated inductive reactance data and sparsely dividing areas with sparse inductive reactance data; densely dividing at the critical inflection point of inductive reactance and at the boundary of intervals where inductive reactance values ​​are prone to fluctuation, and dividing the remaining intervals evenly according to the magnitude of the inductive reactance value.

[0020] The standard current rise variation characteristics refer to the waveform characteristics of the discharge current during the rise phase under ideal operating conditions of the discharge circuit, including the current rise rate, rise time, peak current, and overshoot amplitude, which are used to characterize the dynamic response of the discharge circuit under ideal operating conditions.

[0021] The discharge current time series refers to the waveform of current change formed by the change of discharge current over time during the conduction of the discharge circuit.

[0022] The actual current rise variation characteristics refer to the waveform characteristics of the discharge current during the rising phase under the actual working conditions of the discharge circuit, including the current rise rate, rise time, peak current and overshoot amplitude, etc., which are used to characterize the dynamic response of the discharge circuit under actual working conditions.

[0023] Different threshold levels refer to multiple critical values ​​that classify different degrees of performance degradation in power electronic switching components.

[0024] Performance degradation refers to the degree of performance degradation of power electronic switching components due to aging and wear.

[0025] This method obtains the initial contact resistance and inductive reactance of the discharge circuit, providing fundamental parameters for subsequent diagnosis. Specifically, the impedance characteristics of the circuit can be analyzed and the initial contact resistance and inductive reactance can be calculated by applying small-amplitude AC probe signals of different frequencies to the discharge circuit. For example, a continuously adjustable sinusoidal AC probe signal can be injected into the discharge circuit, and the amplitude and phase feedback information of the probe signal at different frequencies can be collected. Then, the impedance amplitude-frequency characteristic curve and phase-frequency characteristic curve of the circuit can be obtained by fitting, and the initial contact resistance and inductive reactance of the circuit can be analyzed based on the impedance characteristics.

[0026] Based on the obtained inductive reactance value, the standard current rise characteristic corresponding to the current circuit inductance state is retrieved from a preset inductance parameter range. Specifically, this can be achieved by matching the measured inductive reactance value with each inductance parameter range. For example, several inductance parameter ranges can be pre-divided according to the inductive reactance value, and each range can pre-store a corresponding standard current rise characteristic. The real-time detected inductive reactance value is compared with each inductance parameter range to determine the range to which the reactance value belongs, and then the pre-stored standard current rise characteristic for that range is directly retrieved. This step, by matching the actual inductive reactance value with the preset inductance parameter range, ensures that the retrieved standard current rise characteristic reflects the current circuit's inductance characteristics.

[0027] The process involves acquiring the discharge current time series during the discharge circuit's conduction process and obtaining the actual current rise characteristics of the discharge circuit based on this time series. Specifically, a current acquisition module continuously collects discharge current data at fixed time intervals throughout the entire discharge circuit's conduction process to form a complete discharge current time series. Then, a signal analysis module extracts the current rise phase characteristics from the discharge current time series to obtain the actual current rise characteristics. The current acquisition module can be implemented using a Hall effect current sensor, a shunt, or a current transformer; the signal analysis module can be any controller with signal analysis capabilities. This step obtains the dynamic response of the power electronic switching element under actual operating conditions by real-time monitoring of the discharge current, thereby obtaining the current rise characteristics.

[0028] Based on the interference effect of initial contact resistance on the discharge process, the actual current rise variation characteristics are corrected and compensated. Specifically, the waveform interference component caused by the initial contact resistance can be calculated and targeted compensation and correction can be implemented based on this waveform interference component. For example, multiple sets of initial contact resistance samples with different resistance values ​​are pre-selected, and discharge tests are carried out one by one under ideal working conditions. The original current rise waveform corresponding to each set of contact resistance is collected, and the current waveform deviation is obtained by comparing it with the ideal current rise waveform without contact resistance interference. Then, the mapping relationship between the contact resistance value and the current waveform deviation is obtained by fitting, thereby constructing a current waveform interference correction model. The measured value of the initial contact resistance obtained in real time is substituted into the established correction model for parameter matching, and the corresponding interference compensation coefficient is calculated by looking up the table. Then, the amplitude calibration and rise slope correction of the extracted actual current rise variation characteristics are performed using the compensation coefficient, and the waveform offset component caused by the initial contact resistance is eliminated to obtain the corrected actual current rise variation characteristics.

[0029] The corrected actual current rise variation characteristics are compared with the standard current rise variation characteristics, and the characteristic deviation value between the two is calculated. This deviation value quantifies the difference between actual performance and ideal performance.

[0030] The performance degradation state of the power electronic switching element is determined based on the calculated characteristic deviation value and the judgment relationship between preset threshold levels. Specifically, different preset threshold levels correspond to different degrees of performance degradation, and each threshold level is a preset fixed value set in ascending order of degradation degree. When the characteristic deviation value is less than the minimum threshold, the power electronic switching element is determined to have no performance degradation and is in a normal and stable working state. When the characteristic deviation value is greater than or equal to the minimum threshold and less than the maximum threshold, it is determined that the switching element has experienced slight performance degradation and can still maintain normal operation, but performance changes need to be continuously monitored to prevent further deterioration. When the characteristic deviation value is greater than or equal to the highest threshold, it is determined that the switching element has suffered severe performance degradation and is prone to faults such as abnormal discharge, inaccurate action response, and control failure. It needs to be repaired or replaced in time.

[0031] Through the above technical solution, this application is able to perform performance diagnosis on the power electronic switching components in a high-power energy storage projection welding machine, thus solving the technical problem of how to perform performance diagnosis on the power electronic switching components in a high-power energy storage projection welding machine.

[0032] In some preferred embodiments, the step of retrieving the standard current rise characteristic corresponding to the current circuit inductance state from a preset inductance parameter range based on the inductive reactance value includes: Collect the real-time operating temperature of power electronic switching components, or count the cumulative number of discharges within a fixed time period; The equipment is classified and categorized according to its operating temperature range and cumulative discharge frequency, and the corresponding compensation ratio is matched according to the pre-set classification compensation rules. Using this compensation ratio, the initially obtained standard current rise variation characteristics are compensated to obtain standard current rise variation characteristics that are adapted to the current actual working state.

[0033] In this application, the graded compensation rule refers to a lookup table rule that maps the compensation ratio to different levels based on the operating temperature range and the cumulative number of discharges. The compensation ratio corresponding to each level is determined through experimental calibration. The higher the temperature and the more cumulative the discharges, the more significant the drift in inductance and circuit parameters, and the larger the corresponding compensation ratio.

[0034] The system collects the real-time operating temperature of power electronic switching components or counts the cumulative number of discharges within a fixed time period. Specifically, the real-time operating temperature reflects the impact of the current state of the power electronic switching component on the circuit impedance, while the cumulative number of discharges reflects the drift of the switching characteristics due to the aging of the power electronic switching component. This can be achieved by monitoring the surface temperature or internal junction temperature of the power electronic switching component in real time using a temperature sensor, and by counting the number of discharge operations of the power electronic switching component within a specific time period using a counter or data recording module. For example, the temperature sensor collects the temperature data of the power electronic switching component once per second; the discharge counter increments by one each time a discharge occurs within a specific time period, and the cumulative number of discharges is recorded at the end of each hour.

[0035] The components are categorized according to operating temperature range and cumulative discharge frequency. Based on pre-defined compensation rules, corresponding compensation ratios are matched. Specifically, based on the collected real-time operating temperature and cumulative discharge counts, these are divided into several temperature ranges and discharge frequency levels. The compensation ratios for these temperature ranges and frequency levels are then matched according to the compensation rules. For example, operating temperatures are divided into low-temperature, normal-temperature, and high-temperature zones; cumulative discharge counts are divided into low-frequency, medium-frequency, and high-frequency levels. Under high-temperature and high-frequency operating conditions, power electronic switching components require a larger compensation ratio to correct for the rising characteristics of the standard current.

[0036] This compensation ratio is used to compensate for the initially obtained standard current rise variation characteristics, resulting in standard current rise variation characteristics adapted to the current actual operating conditions. Specifically, the compensation ratio can be used as a scaling factor to adjust the amplitude or slope of the initially obtained standard current rise variation characteristics. If the current temperature is high or the cumulative number of discharges is high, the waveform parameters can be amplified or fine-tuned by the compensation ratio to offset the deviation caused by drift; if the current equipment operating conditions are close to ideal, a small compensation is sufficient.

[0037] Through the above technical solution, this application solves the problem that the standard current rise change characteristics retrieved based solely on the inductive reactance value cannot be adapted to the actual working state. This is because factors such as the real-time operating temperature and cumulative discharge count of power electronic switching components can also affect the inductance state and current rise change characteristics of the circuit, resulting in a deviation between the retrieved standard characteristics and the actual situation, thereby affecting the accuracy of fault diagnosis.

[0038] In some preferred embodiments, the step of acquiring the discharge current time series during the discharge circuit conduction process includes: The transient current signal in the discharge circuit is acquired using a current acquisition unit. The current acquisition unit has DC response capability and its operating frequency band is not less than 100 kHz. The transient current signal is discretized and digitized using an analog-to-digital conversion unit at a sampling rate of no less than one million times per second to generate a discharge current time series.

[0039] In this application, the current acquisition unit is a device used to convert transient current signals in the discharge circuit into electrical signals that can be processed subsequently. Specifically, it can be implemented using a Hall effect current sensor, a shunt, or a current transformer. Hall effect current sensors enable non-contact measurement, have DC response capability, and a wide bandwidth. Shunts indirectly measure current by measuring the voltage drop across a known resistor, requiring a low-inductance design to ensure high-frequency response. Current transformers measure current through electromagnetic induction, but typically lack DC response capability. Therefore, in this solution, a Hall effect current sensor or a specially designed wideband shunt is preferred.

[0040] DC response capability refers to the ability of a current acquisition unit to accurately measure both DC current components and low-frequency AC current components.

[0041] An analog-to-digital converter (ADC) is a device that converts analog electrical signals into digital signals. Specifically, it can be implemented using a high-speed analog-to-digital converter.

[0042] Discretization sampling and digitization processing refers to the process by which an analog-to-digital converter discretizes a continuous analog transient current signal in time and quantizes it in amplitude, ultimately converting it into a series of digital values.

[0043] The operating frequency band is no less than 100 kHz. Specifically, the transient current signal during the discharge circuit conduction process usually contains rich harmonic components and rapidly changing rising edges. The high-frequency response capability ensures that the current acquisition unit can capture these rapidly changing current details and avoid signal distortion or information loss due to frequency band limitations.

[0044] A sampling rate of no less than one million times per second is required. Specifically, a high sampling rate ensures precise capture of transient current signals and effectively avoids information loss caused by insufficient sampling.

[0045] Through the above technical solution, this application solves the problem that conventional current acquisition and sampling processing is difficult to accurately capture the details of discharge transient current, and is prone to losing DC components and high-frequency characteristics. Because the transient current of the discharge circuit changes rapidly and contains effective DC components and high-frequency components, the bandwidth of ordinary acquisition units is limited and the sampling rate is insufficient, which easily causes the loss of current details, signal aliasing and loss of effective information. As a result, the generated current time series cannot truly restore the actual current change law of the discharge circuit, thus affecting the accuracy of subsequent fault diagnosis.

[0046] In some preferred embodiments, the steps of obtaining the initial contact resistance and inductive reactance of the discharge circuit include: Before discharging, a detection signal is injected into the discharge circuit and a feedback signal is collected. The initial contact resistance of the discharge circuit is obtained by analyzing the feedback signal. The phase shift information generated by the transmission of the detection signal in the discharge circuit is collected to identify the current inductive reactance value of the discharge circuit.

[0047] In this application, the detection signal refers to an AC signal, such as a sine wave, square wave, or pulse signal, the frequency and amplitude of which need to be selected according to the characteristics of the discharge circuit to ensure that it does not interfere with the circuit.

[0048] Phase offset information refers to the phase difference between the feedback signal and the probe signal in the time domain.

[0049] Feedback signals can be acquired by setting voltage and current probes in the discharge circuit, which can monitor voltage and current changes in the circuit in real time.

[0050] The initial contact resistance of the discharge circuit is obtained by analyzing the feedback signal. Specifically, the total impedance of the discharge circuit is calculated based on the amplitude attenuation and phase change of the measured feedback signal relative to the probe signal, and then the known fixed resistance of the circuit is removed to obtain the initial contact resistance.

[0051] The phase shift information generated during the transmission of the detection signal in the discharge circuit is acquired. Specifically, due to the presence of inductive components in the circuit, the feedback signal may lag or lead the detection signal in phase when the detection signal is transmitted through the discharge circuit. The phase shift information can be acquired using a lock-in amplifier or a digital oscilloscope.

[0052] Identify the inductive reactance of the current discharge circuit. Specifically, the inductive reactance can be calculated using phase shift information and the frequency of the probe signal. For example, for an RL circuit, the phase shift angle φ has a relationship of tan(φ) = XL / R with respect to the inductive reactance XL and the resistance R. Therefore, given the resistance R and the phase shift φ, the inductive reactance XL = R * tan(φ) can be calculated. If the probe signal is a multi-frequency signal, the inductive reactance can be identified more accurately by analyzing the phase shift at different frequencies, and even the frequency response curve of the circuit can be constructed.

[0053] Through the above technical solution, this application solves the problem of how to accurately obtain the initial contact resistance and inductive reactance of the discharge circuit during the performance diagnosis of energy storage welding equipment.

[0054] In some preferred embodiments, the step of obtaining the actual current rise characteristics of the discharge circuit based on the discharge current time series includes: Identify the current start point and current peak point in the discharge current time series; Within the current rise interval from the current initiation point to the current peak point, the data sequence corresponding to the preset proportion interval is extracted as the target data segment; Based on the phase shift information, the inherent resonant frequency of the discharge circuit is identified; The cutoff frequency is set according to the inherent resonant frequency, and the target data segment is smoothed according to the cutoff frequency. The change in the rate of current rise is calculated for the smoothed target data segment to obtain the actual characteristics of the current rise.

[0055] In this application, the preset ratio range refers to a local selection range defined by the current rise range according to a preset percentage or a specified time window.

[0056] The inherent resonant frequency is an inherent property of a circuit, reflecting the interaction between inductance and capacitance within the circuit.

[0057] The cutoff frequency refers to the critical frequency at which a filter defines the passband and stopband of a signal.

[0058] Identify the current start point and current peak point in the discharge current time series. Specifically, determine the moment when the current begins to rise and the moment when the current reaches its maximum value by analyzing the current time series data. This can be achieved using a threshold detection method. For example, when the current value continuously exceeds a certain preset small threshold, it is marked as the current start point; when the current value reaches a local maximum value and then begins to decline, it is marked as the current peak point.

[0059] Within the current rise interval from the current initiation point to the current peak point, a data sequence corresponding to a preset percentage interval is extracted as the target data segment. Specifically, after determining the effective current rise interval, a portion of data is selected from this interval for subsequent processing. This can be achieved using a percentage-based extraction method; for example, 80% of the data within the current rise interval can be extracted as the target data segment, or data within a specific time window can be extracted according to actual needs. This extraction method allows subsequent processing to focus on the key data that best reflects the current rise characteristics, avoiding interference from irrelevant data in feature extraction.

[0060] Based on the phase shift information, the inherent resonant frequency of the discharge circuit is identified. Specifically, by injecting probe signals of different frequencies into the circuit and measuring the phase shift of the feedback signal, a phase-frequency curve is plotted, and the inherent resonant frequency of the circuit is obtained from the phase-frequency curve.

[0061] A cutoff frequency is set based on the inherent resonant frequency, and the target data segment is smoothed according to this cutoff frequency. Specifically, the cutoff frequency of the filter is set using the inherent resonant frequency to remove noise from the target data segment. This can be achieved using a low-pass filter. For example, the cutoff frequency can be set slightly higher than or equal to the inherent resonant frequency. Then, digital filtering and smoothing are performed on the target data segment, which can effectively filter out high-frequency noise and unnecessary fluctuations in the target data segment, making the current rising trend clearer and laying the foundation for subsequent feature calculations.

[0062] The change in the rate of current rise is calculated for the smoothed target data segment to obtain the actual characteristics of the current rise. Specifically, the change in the rate of current rise of the target data segment is calculated using the difference method or the fitting method. For example, the ratio of the difference between adjacent points in the target data segment to the time interval can be calculated to obtain the instantaneous rate of current rise; or the smoothed target data segment can be curve-fitted, and then the derivative of the fitted curve can be calculated to obtain the change in the rate of current rise.

[0063] Through the above technical solution, this application can effectively filter out noise and unnecessary fluctuations in the discharge current time series, thereby more accurately identifying the current rise change characteristics, solving the problem of inaccurate results caused by directly calculating the current rise change characteristics based on the original data, and improving the accuracy of subsequent performance degradation state determination.

[0064] In some preferred embodiments, the step of comparing the corrected actual current rise variation characteristics with the standard current rise variation characteristics and calculating the characteristic deviation value between the two includes: Calculate the root mean square value or peak-to-peak value of the actual current rise and change characteristics, and compare the root mean square value or peak-to-peak value with the standard root mean square value or standard peak-to-peak value corresponding to the standard current rise and change characteristics to obtain the mean square error or peak deviation. The calculated mean square error or peak deviation is used as the characteristic deviation value.

[0065] In this application, the root mean square value can reflect the effective value of the current waveform, that is, its energy magnitude; the peak-to-peak value can reflect the maximum instantaneous change amplitude of the current waveform.

[0066] The characteristic deviation value refers to the difference between the actual current rise and change characteristics and the standard current rise and change characteristics, which can be expressed as mean square error or peak deviation.

[0067] To calculate the root mean square (RMS) or peak-to-peak value of the actual current rise and change characteristics, specifically, the RMS value is obtained by squaring the instantaneous values ​​of the current rise and change characteristics, averaging them, and then taking the square root. The peak-to-peak value is obtained by identifying the maximum and minimum values ​​in the current rise and change characteristics and then calculating the difference between the two.

[0068] The root mean square (RMS) value or peak-to-peak value is compared with the standard RMS value or standard peak-to-peak value corresponding to the standard current rise and change characteristics to obtain the mean square error or peak deviation. Specifically, the mean square error is obtained by averaging the square of the difference between the actual RMS value and the standard RMS value; the peak deviation is obtained by calculating the absolute value of the difference between the actual peak-to-peak value and the standard peak-to-peak value.

[0069] The calculated mean square error or peak deviation is used as the characteristic deviation value for subsequent performance degradation determination.

[0070] By employing the aforementioned technical solution, this method accurately assesses the difference between the actual and standard current rise characteristics by calculating the characteristic deviation between them, thereby quantifying the difference between the actual and standard waveforms. Therefore, this solution provides a reliable basis for determining the performance degradation state of power electronic switching components, improving the accuracy and reliability of the diagnostic process.

[0071] In some preferred embodiments, the step of determining the performance degradation state of the power electronic switching element based on the relationship between the characteristic deviation value and preset threshold values ​​of different levels includes: The feature deviation value is compared with the preset threshold values ​​of different levels one by one; The degree of attenuation is obtained based on the comparison results, and the performance degradation state of the power electronic switching element is determined based on the degree of attenuation. Based on the determined performance degradation status, output the corresponding diagnostic warning information.

[0072] In this application, the degree of degradation refers to the severity of the performance degradation of power electronic switching components, which is divided into mild degradation and severe degradation. Mild degradation means that the performance has begun to decline, but the device can still continue to operate. Severe degradation means that the performance has been severely degraded and there is a risk of failure.

[0073] Diagnostic warning information refers to prompts used to indicate equipment failure or performance degradation, providing intuitive feedback on the health status of power electronic switching components.

[0074] The characteristic deviation value is compared with preset threshold values ​​of different levels one by one. The degree of attenuation is obtained based on the comparison results, and the performance degradation state of the power electronic switching element is determined based on this degree of attenuation. Specifically, multiple threshold ranges can be obtained based on different threshold levels, each corresponding to a different degree of attenuation. By comparing the characteristic deviation value with different threshold levels, the threshold range to which the characteristic deviation value belongs can be determined, thereby determining the degree of attenuation and performance degradation state of the power electronic switching element. For example, when the characteristic deviation value is in the low threshold range, it is defined as slight attenuation, and the power electronic switching element is determined to be in a performance degradation state; when the characteristic deviation value is in the high threshold range, it is defined as severe attenuation, and the power electronic switching element is determined to be in a failure risk state.

[0075] Based on the determined performance degradation status, corresponding diagnostic warning information is output. Specifically, the performance degradation determination results of power electronic switching components are transformed into standardized diagnostic warning information, which intuitively reflects the health status of the power electronic switching components. This, in turn, reminds maintenance personnel to carry out monitoring, calibration, or replacement and repair as needed, achieving early warning of performance degradation and ensuring the safe and reliable operation of equipment.

[0076] Through the above technical solution, this application solves the problems of how to specifically obtain the degree of attenuation based on the comparison results, determine the performance attenuation state of the power electronic switching element based on the degree of attenuation, and output corresponding diagnostic warning information based on the determined performance attenuation state during the performance attenuation diagnosis process of power electronic switching elements. This solution can provide refined attenuation degree determination, making the diagnostic results more accurate and enabling the output of clear warning information, thereby improving the effectiveness of the warning information and facilitating timely maintenance measures to ensure the safe and stable operation of the equipment.

[0077] In some preferred embodiments, the preset different level thresholds include a first preset threshold and a second preset threshold; the step of obtaining the attenuation degree based on the comparison result and determining the performance degradation state of the power electronic switching element based on the attenuation degree includes: When the characteristic deviation value exceeds the first preset threshold but is lower than the second preset threshold, the attenuation degree is mild attenuation, and the power electronic switching element is determined to be in a state of performance degradation. When the characteristic deviation value exceeds the second preset threshold, the attenuation degree is severe attenuation, and the power electronic switching element is determined to be in a state of failure risk. The standard root mean square value or standard peak-to-peak value corresponding to the standard current rise change characteristics are used as the normal reference value. The first preset threshold is configured as follows: the deviation of its root mean square error from the normal reference value reaches 5%, or the deviation of its peak value from the normal reference value reaches 10%. The second preset threshold is configured as follows: the deviation of its root mean square error from the normal reference value reaches 15%, or the deviation of its peak value from the normal reference value reaches 20%.

[0078] The preset threshold levels refer to quantitative standards used to distinguish the degree of performance degradation of power electronic switching components, specifically including a first preset threshold and a second preset threshold. These thresholds can be adjusted according to actual application scenarios and equipment reliability requirements.

[0079] In this application, the first preset threshold and the second preset threshold are parameters used to classify and determine the feature deviation values. The first preset threshold is used to identify mild attenuation, while the second preset threshold is used to identify severe attenuation and failure risk.

[0080] Performance degradation state refers to the current operating state of power electronic switching components, including normal operation, performance degradation, and failure risk.

[0081] The normal reference value refers to the standard root mean square value or standard peak-to-peak value corresponding to the standard current rise characteristic of a power electronic switching element under normal operating conditions. This reference value serves as a reference point for deviation calculation, ensuring the objectivity and accuracy of threshold setting.

[0082] The first preset threshold is configured as follows: the mean square error deviates by 5% from the normal reference value, or the peak value deviates by 10% from the normal reference value. This means that when the mean square error or peak value deviation reaches these proportions, the component is considered to have entered a slightly degraded state. These values ​​are set based on experience or experimental data to balance the sensitivity and false alarm rate of the diagnosis.

[0083] The second preset threshold is configured as follows: the mean square error deviates by 15% from the normal reference value, or the peak value deviates by 20% from the normal reference value. These values ​​are used to identify more severe performance degradation; when the deviation reaches these proportions, the component is considered to be at risk of failure. These values ​​are typically higher than the first preset threshold to ensure that a failure risk warning is only issued when performance deteriorates significantly.

[0084] When the characteristic deviation value is lower than the first preset threshold, the system determines that the attenuation level is normal and the power electronic switching element is in normal performance condition.

[0085] When the characteristic deviation value exceeds a first preset threshold but falls below a second preset threshold, the system determines the attenuation level to be mild and further determines that the power electronic switching element is in a performance degradation state. This graded determination mechanism can identify early or slight performance degradation.

[0086] When the characteristic deviation value exceeds the second preset threshold, the system determines the attenuation level to be severe and further determines that the power electronic switching element is in a state of failure risk. This determination mechanism can identify severe performance degradation, indicating that the equipment may be about to fail, thereby avoiding potential faults and safety hazards.

[0087] This solution introduces clearly defined first and second preset thresholds, and achieves refined judgment of the performance degradation state of power electronic switching components based on the comparison of characteristic deviation values ​​with these thresholds. This hierarchical threshold setting enables the system to accurately and hierarchically diagnose the performance degradation state of power electronic switching components, improving the precision and practicality of fault diagnosis.

[0088] Through the above technical solution, this application solves the problem of how to specifically set different level thresholds when determining the performance degradation state of power electronic switching components, and how to accurately distinguish between mild degradation and severe degradation based on these thresholds, and further determine the failure risk state.

[0089] In some preferred embodiments, the step of outputting diagnostic warning information corresponding to the status includes: The fault warning information includes structured information such as the time of fault occurrence, fault type, location of affected components, and degree of attenuation; Diagnostic and early warning information is transmitted to the monitoring terminal in real time via an industrial communication bus for text display or audible and visual alarms; the industrial communication bus includes industrial Ethernet or RS485 bus.

[0090] In this application, the fault occurrence time can be accurate to the second, used to record the specific moment the fault occurred. Fault types can include overvoltage, overcurrent, abnormal temperature, insulation aging, etc., used to describe the nature of the fault. The location of the affected component can indicate which specific part of the power electronic switching element the fault occurred in, such as a branch or drive circuit of an IGBT module. The degree of degradation can be categorized based on the performance degradation status, such as mild degradation, severe degradation, or failure risk. This structured information ensures the completeness and standardization of the early warning information, facilitating subsequent analysis and processing.

[0091] The system outputs diagnostic and early warning information corresponding to the given status. Specifically, this information can be transmitted in real-time to the monitoring terminal via an industrial communication bus. This industrial communication bus can include industrial Ethernet or RS485. Industrial Ethernet features high bandwidth and high speed, making it suitable for transmitting large amounts of data and implementing complex network topologies. RS485 offers advantages such as simple wiring, strong anti-interference capabilities, and long transmission distances, making it suitable for point-to-multipoint communication. Through these industrial communication buses, diagnostic and early warning information can be transmitted to the monitoring terminal in real-time. The monitoring terminal can then display text or issue audible and visual alarms based on the received information, thereby achieving timely and accurate fault warnings and handling.

[0092] Through the above technical solution, this application solves the problem of structuring and real-time transmission of diagnostic early warning information. By including structured information such as the fault occurrence time, fault type, location of affected components, and attenuation level in the diagnostic early warning information, the integrity and standardization of the early warning information are ensured, facilitating subsequent analysis and processing. Based on this, this structured information is transmitted to the monitoring terminal in real time via an industrial communication bus, achieving timely delivery of diagnostic early warning information. This real-time transmission mechanism enables the monitoring terminal to immediately receive the early warning information and display it in text or with audible and visual alarms, thereby enabling rapid response and appropriate measures. This effectively avoids potential risks caused by information delays and improves the efficiency and reliability of fault diagnosis.

[0093] refer to Figure 2 This application provides a fault diagnosis system for a high-power energy storage projection welding machine, the system comprising: Data acquisition module 1 is used to acquire the initial contact resistance and inductive reactance of the discharge circuit (the specific process can be found in the previous text). The retrieval module 2 is used to retrieve the standard current rise change characteristics corresponding to the current circuit inductance state from the preset inductance parameter range based on the inductive reactance value (the specific process can be referred to above). The data acquisition and extraction module 3 is used to acquire the discharge current time series during the discharge circuit conduction process, and obtain the actual current rise and change characteristics of the discharge circuit based on the discharge current time series (the specific process can be referred to above). The compensation and comparison module 4 is used to correct and compensate the actual current rise and change characteristics based on the interference effect of the initial contact resistance on the discharge process; then, it compares the corrected actual current rise and change characteristics with the standard current rise and change characteristics to calculate the characteristic deviation value between the two (the specific process can be referred to above). The state determination module 5 is used to determine the performance degradation state of the power electronic switching element based on the determination relationship between the characteristic deviation value and the preset threshold values ​​of different levels (the specific process can be referred to above).

[0094] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A fault diagnosis method for a high-power energy storage projection welding machine, used for performance diagnosis of energy storage welding equipment, wherein the energy storage welding equipment includes a discharge circuit and a power electronic switching element disposed in the discharge circuit, characterized in that, The steps of this method include: Obtain the initial contact resistance and inductive reactance of the discharge circuit; Based on the inductive reactance value, the standard current rise and change characteristics corresponding to the current circuit inductance state are retrieved from the preset inductance parameter range. The discharge current time series during the discharge circuit conduction process is collected, and the actual current rise and change characteristics of the discharge circuit are obtained based on the discharge current time series. Based on the interference effect of the initial contact resistance on the discharge process, the actual current rise and change characteristics are corrected and compensated, and then the corrected actual current rise and change characteristics are compared with the standard current rise and change characteristics to calculate the characteristic deviation value between the two. The performance degradation state of the power electronic switching element is determined based on the relationship between the characteristic deviation value and preset threshold values ​​of different levels. The step of retrieving the standard current rise characteristic corresponding to the current circuit inductance state from a preset inductance parameter range based on the inductive reactance value includes: Collect the real-time operating temperature of power electronic switching components, or count the cumulative number of discharges within a fixed time period; The equipment is classified and categorized according to its operating temperature range and cumulative discharge frequency, and the corresponding compensation ratio is matched according to the pre-set classification compensation rules. Using this compensation ratio, the initially obtained standard current rise variation characteristics are compensated to obtain standard current rise variation characteristics that are adapted to the current actual working state. The steps for obtaining the initial contact resistance and inductive reactance of the discharge circuit include: Before discharging, a detection signal is injected into the discharge circuit and a feedback signal is collected. The initial contact resistance of the discharge circuit is obtained by analyzing the feedback signal. The phase shift information generated by the transmission of the detection signal in the discharge circuit is collected to identify the current inductive reactance value of the discharge circuit; The step of comparing the corrected actual current rise variation characteristics with the standard current rise variation characteristics and calculating the characteristic deviation value between the two includes: Calculate the root mean square value or peak-to-peak value of the actual current rise change characteristic, and compare the root mean square value or peak-to-peak value with the standard root mean square value or standard peak-to-peak value corresponding to the standard current rise change characteristic to obtain the mean square error or peak deviation. The calculated mean square error or peak deviation is used as the characteristic deviation value.

2. The fault diagnosis method for a high-power energy storage projection welding machine according to claim 1, characterized in that, The steps for acquiring the discharge current time series during the discharge circuit conduction process include: The transient current signal in the discharge circuit is acquired using a current acquisition unit. The current acquisition unit has DC response capability and its operating frequency band is not less than 100 kHz. The transient current signal is discretized and digitized using an analog-to-digital conversion unit at a sampling rate of not less than one million times per second to generate the discharge current time series.

3. The fault diagnosis method for a high-power energy storage projection welding machine according to claim 1, characterized in that, The step of obtaining the actual current rise characteristics of the discharge circuit based on the discharge current time series includes: Identify the current start point and current peak point in the discharge current time series; Within the current rise interval from the current starting point to the current peak point, the data sequence corresponding to the preset proportion interval is extracted as the target data segment; Based on the phase shift information, the inherent resonant frequency of the discharge circuit is identified; A cutoff frequency is set according to the inherent resonant frequency, and the target data segment is smoothed according to the cutoff frequency. The change in the rate of current rise is calculated for the smoothed target data segment to obtain the actual current rise characteristics.

4. The fault diagnosis method for a high-power energy storage projection welding machine according to claim 1, characterized in that, The step of determining the performance degradation state of the power electronic switching element based on the relationship between the characteristic deviation value and preset threshold values ​​of different levels includes: The feature deviation value is compared with preset threshold values ​​of different levels one by one; The degree of attenuation is obtained based on the comparison results, and the performance degradation state of the power electronic switching element is determined based on the degree of attenuation. Based on the determined performance degradation state, output corresponding diagnostic warning information.

5. A fault diagnosis method for a high-power energy storage projection welding machine according to claim 4, characterized in that, The preset different level thresholds include a first preset threshold and a second preset threshold; The step of obtaining the attenuation level based on the comparison results and determining the performance degradation state of the power electronic switching element based on the attenuation level includes: When the characteristic deviation value exceeds the first preset threshold and is lower than the second preset threshold, the attenuation degree is mild attenuation, and the power electronic switching element is determined to be in a performance degradation state. When the characteristic deviation value exceeds the second preset threshold, the attenuation degree is severe attenuation, and the power electronic switching element is determined to be in a state of failure risk. Using the standard root mean square value or standard peak-to-peak value corresponding to the standard current rise change characteristics as the normal reference value, the first preset threshold is configured as follows: the deviation of its root mean square error from the normal reference value reaches 5%, or the deviation of its peak value from the normal reference value reaches 10%; the second preset threshold is configured as follows: the deviation of its root mean square error from the normal reference value reaches 15%, or the deviation of its peak value from the normal reference value reaches 20%.

6. The fault diagnosis method for a high-power energy storage projection welding machine according to claim 4, characterized in that, The diagnostic warning information includes structured information such as the time of fault occurrence, fault type, location of affected components, and degree of attenuation. The steps for outputting diagnostic warning information corresponding to the state include: The diagnostic warning information is transmitted to the monitoring terminal in real time via an industrial communication bus for text display or audible and visual alarms. The industrial communication bus includes industrial Ethernet or RS485 bus.

7. A fault diagnosis system for a high-power energy storage projection welding machine, used to execute the fault diagnosis method for a high-power energy storage projection welding machine as described in any one of claims 1 to 6, characterized in that, include: The data acquisition module is used to acquire the initial contact resistance and inductive reactance of the discharge circuit; The retrieval module is used to retrieve the standard current rise change characteristics corresponding to the current circuit inductance state from a preset inductance parameter range based on the inductive reactance value. The data acquisition and extraction module is used to acquire the discharge current time series during the discharge circuit conduction process, and obtain the actual current rise and change characteristics of the discharge circuit based on the discharge current time series. The compensation and comparison module is used to correct and compensate the actual current rise and change characteristics based on the interference effect of the initial contact resistance on the discharge process; then, it compares the corrected actual current rise and change characteristics with the standard current rise and change characteristics to calculate the characteristic deviation value between the two. The status determination module is used to determine the performance degradation status of power electronic switching components based on the determination relationship between the characteristic deviation value and preset different level thresholds.

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