A method and system for detecting the degradation of insulating packaging materials based on molecular vibrations

Abstract

This invention relates to the field of electrical equipment insulation condition testing technology, specifically a method and system for detecting the degradation of insulating encapsulation materials based on molecular vibrations. The method includes applying a periodic high-voltage square wave pulse voltage to the insulating encapsulation material sample under test, detecting the molecular vibration acoustic wave signal excited by the transient electric field force, capturing the transient molecular vibration waveform within a specific acquisition window after the pulse edge, extracting multi-dimensional features from the acquired transient molecular vibration waveform, inputting the extracted multi-dimensional features into a pre-constructed evaluation model or comparing them with a preset threshold, and outputting the current degradation degree or degradation assessment result of the insulating encapsulation material under test. By extracting the time-domain amplitude, waveform morphology, relaxation time, and wavelet packet entropy of the vibration waveform through multi-dimensional feature extraction, and employing a dual criterion of mechanical damage and energy dissociation, the degradation degree of the insulating encapsulation material is assessed.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment insulation condition detection technology, specifically to a method and system for detecting the deterioration of insulating packaging materials based on molecular vibration. Background Technology

[0002] Insulating encapsulation materials are critical components in power equipment and electronic devices, and their performance directly affects the operational reliability and service life of the equipment. Under long-term high-frequency, high-voltage square wave pulse stress, the insulating encapsulation materials of high-voltage power devices are prone to deterioration and failure due to the complex and harsh operating environment. Therefore, online degradation assessment of insulation condition is essential.

[0003] Electroacoustic pulse (PEA) is a widely used space charge measurement technique. Its basic principle involves superimposing a high-voltage DC bias and a nanosecond-level Gaussian pulse onto an insulating encapsulation material. A piezoelectric sensor detects the acoustic waves excited by the movement of space charges, thereby retrieving the charge distribution. However, the PEA method has several limitations in the online monitoring of practical power devices: first, the excitation source is mismatched, with the Gaussian pulse deviating from the actual square-wave voltage condition of the device; second, the system is complex, requiring an additional pulse generator, which is bulky and costly; and third, the information dimension is limited, as PEA primarily outputs the static distribution density of space charges, failing to directly reflect the fatigue evolution and degradation trend of the material. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for detecting the degradation of insulating packaging materials based on molecular vibrations, comprising:

[0005] S1. Apply a periodic high-voltage square wave pulse voltage simulating the actual operating conditions of a high-voltage power device to the insulating encapsulation material under test, and generate a trigger signal that is precisely synchronized with the rising or falling edge of the periodic high-voltage square wave pulse voltage.

[0006] S2. Based on the edge effect of high voltage square wave pulse voltage, the sensor detects the molecular vibration acoustic wave signal excited by the internal charge of the insulating packaging material under test driven by the transient electric field force, and converts the molecular vibration acoustic wave signal into an electrical signal.

[0007] S3. Based on the synchronous trigger signal, the converted electrical signal is synchronously acquired to capture the transient molecular vibration waveform within a specific acquisition window after the pulse edge.

[0008] S4. Perform multi-dimensional feature extraction on the acquired transient molecular vibration waveform to obtain the time-domain amplitude features, waveform morphology features, relaxation time feature constants, and wavelet packet entropy of the vibration waveform;

[0009] S5. Input the multi-dimensional features of the extracted transient molecular vibration waveform into the pre-built evaluation model or compare it with the preset threshold, and output the qualitative judgment or degradation assessment result of the current degree or trend of degradation of the insulating packaging material under test.

[0010] The specific operation of comparing the extracted multi-dimensional features with a preset threshold as described in S5 is as follows:

[0011] Key fracture risk assessment based on time-domain amplitude characteristics of vibration waveform;

[0012] Based on the equivalent alternating stress amplitude determined by the mechanical failure criterion and the relaxation time characteristic constant of the vibration waveform, the aging rate is evaluated according to the energy dissociation criterion.

[0013] The degradation state of the insulating encapsulation material under test is quantitatively assessed based on both mechanical failure criteria and energy dissociation criteria.

[0014] The key fracture risk assessment based on the time-domain amplitude characteristics of the vibration waveform as a mechanical failure criterion includes:

[0015] The extracted time-domain amplitude features are normalized to obtain the equivalent amplitude A of the molecular vibration peak signal. norm By combining the sensitivity S of the piezoelectric sensor with the acoustic impedance characteristics of the insulating encapsulation material, the equivalent alternating stress amplitude σ acting on the molecular chain is calculated. vib According to the equivalent alternating stress amplitude σ vib Determine the equivalent displacement d' of bonding atoms caused by the electric field force pulling the charge;

[0016] The calculated equivalent displacement d' is compared with the critical breaking distance d of the chemical bonds of the insulating encapsulation material to be tested. If d' ≥ d, the insulating encapsulation material to be tested is in a high-risk deterioration state.

[0017] The bond fracture risk coefficient R is obtained from the ratio of the equivalent displacement d' to the critical failure distance d. f When R f If R ≥ 1, a degradation risk warning will be issued; if R f If the value is greater than 1 and continues to increase, the insulating encapsulation material is in a state of accelerated deterioration.

[0018] The aging rate assessment based on the energy dissociation criterion includes:

[0019] The equivalent alternating stress amplitude σ vib Substituting the applied stress σ into the formula for bond fracture frequency:

[0020]

[0021] in,h The bond breaking frequency; n 0 represents the atomic thermal vibration frequency. U 0 represents the dissociation energy under no stress. β For material constants, k Boltzmann's constant, T For testing temperature;

[0022] Define aging acceleration factors A f The bond breakage frequency under the current stress state h Bond breakage frequency under stress-free conditions h 0 The ratio;

[0023]

[0024]

[0025] If aging acceleration factor A f Increase and relax time characteristic constant t If the growth is synchronous, it is determined that the insulating encapsulation material under test is in a state of accelerated deterioration.

[0026] The evaluation model described in S5 uses the Insulation Health Index (IHI), and its formula is as follows:

[0027]

[0028] In the formula, w1, w2, and w3 represent weighting coefficients, respectively; A norm Indicates the equivalent amplitude; t is the relaxation time characteristic constant; Sw is the wavelet packet entropy.

[0029] The specific method for obtaining the wavelet packet entropy of the vibration waveform in S4 is as follows:

[0030] The raw molecular vibration signal acquired in the window after the pulse edge is preprocessed, and the preprocessed vibration signal is decomposed into N-level wavelet packets to obtain 2 N The wavelet packet decomposition coefficients of each frequency band, where N is an integer not less than 3;

[0031] Calculate the energy Ei of each frequency band decomposition coefficient, i=1,2,…,2 N And calculate the total signal energy. ;

[0032] Calculate the energy probability distribution of each frequency band based on the total signal energy. ;

[0033] The wavelet packet entropy is calculated using the information entropy formula, which is:

[0034] .

[0035] In a specific implementation, S4 extracts the relaxation time constant by using Prony series fitting. t .

[0036] S4 also includes edge time normalization correction based on molecular vibration amplitude, specifically:

[0037] Based on molecular vibration amplitude A and pulse edge time t r Based on the empirical relationship model, the normalized correction formula for the pulse edge time and the standard reference edge time is established as follows:

[0038]

[0039] Among them, A p Indicates the measured vibration amplitude; A norm Indicates the equivalent amplitude; t r Indicates the pulse edge time; t ref Indicates the standard reference edge time;

[0040] The actual measurement will be performed at different edge times t. r The vibration amplitude A below p Normalized to standard reference edge time t ref The equivalent amplitude A below norm .

[0041] Another aspect of the present invention provides a molecular vibration-based insulation packaging material degradation detection system for implementing the molecular vibration-based insulation packaging material degradation detection method described above, comprising a high-voltage square wave pulse power supply, a synchronization control circuit, an electrothermal coupling test unit, a broadband signal amplifier, and a digital oscilloscope; the output terminal of the high-voltage square wave pulse power supply is electrically connected to the synchronization control circuit and the electrothermal coupling test unit respectively, the synchronization control circuit is connected to the external trigger channel of the digital oscilloscope; the output terminal of the electrothermal coupling test unit is connected to the digital oscilloscope via the broadband signal amplifier;

[0042] The high-voltage square wave pulse power supply is used to generate periodic high-voltage square wave pulses with adjustable voltage amplitude, repetition frequency and edge time to simulate real working conditions.

[0043] The synchronization control circuit is used to synchronously transmit the high-voltage square wave pulse to the digital oscilloscope, triggering the digital oscilloscope to accurately capture the edge of the square wave pulse, so that the acquisition window of the digital oscilloscope is precisely aligned with the pulse edge.

[0044] The electrothermal coupling test unit is used to place the insulating encapsulation material sample to be tested, and input a high-voltage square wave pulse from a high-voltage square wave pulse power supply to test the insulating encapsulation material sample, obtain the acoustic signal of molecular vibration of the insulating encapsulation material sample to be tested, and convert it into an electrical signal.

[0045] A broadband signal amplifier is used to amplify the electrical signal output by the electrothermal coupling test unit and transmit it to a digital oscilloscope for signal acquisition.

[0046] Digital oscilloscopes are used to capture and store the original vibration waveform based on the electrical signal of the key phase window at the edge of the square wave pulse.

[0047] The electrothermal coupling test unit uses an aluminum lower electrode and a copper cylindrical upper electrode to define the test cavity. The insulating encapsulation material sample to be tested is filled between the upper and lower test electrodes. The interface is coated with silicone oil to reduce sound transmission loss. A semiconducting dielectric layer is laid between the upper electrode and the sample to optimize the electric field distribution. A ceramic insulated heating coil and a temperature monitoring module are configured inside the cavity. The lower electrode is coupled with a PVDF piezoelectric sensor.

[0048] Beneficial effects: This invention is a method and system for detecting the degradation of insulating packaging materials based on molecular vibration. This invention does not require the application of Gaussian pulses, but directly uses the rising and falling edges of high-voltage square wave pulses to excite and detect the molecular vibration signals inside the insulating packaging materials. The high-voltage square wave pulse is synchronized with the external trigger channel of the digital oscilloscope through a synchronization control circuit, so that the acquisition window is precisely aligned with the pulse edge, ensuring the capture of transient molecular vibration waveforms within a specific window after the pulse edge, thereby improving the time resolution and accuracy of the signal.

[0049] Meanwhile, by extracting the time-domain amplitude, waveform morphology, relaxation time, and wavelet packet entropy of the vibration waveform through multi-dimensional feature extraction, it covers degradation dimensions such as material mechanical failure, structural disorder, and chain segment motion. By combining edge time normalization correction to eliminate excitation condition interference, it adopts dual criteria of mechanical failure and energy dissociation to realize the degradation degree assessment of insulating encapsulation materials, thereby improving the accuracy and robustness of the assessment. Attached Figure Description

[0050] The solutions and advantages of this application will become clear to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0051] In the attached diagram:

[0052] Figure 1 This is a flowchart of a method for detecting the degradation of insulating packaging materials based on molecular vibrations;

[0053] Figure 2This is a structural diagram of the insulation encapsulation material degradation detection system of the present invention;

[0054] 1. Upper electrode; 2. Lower electrode; 3. Piezoelectric sensor; 4. Insulating encapsulation material sample to be tested; 5. Heating coil. Detailed Implementation

[0055] Exemplary embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings.

[0056] Example 1

[0057] See Figure 2 This embodiment provides a degradation detection system for insulating packaging materials using a molecular vibration-based degradation detection method. The system includes a high-voltage square wave pulse power supply, a synchronization control circuit, an electrothermal coupling test unit, a broadband signal amplifier, and a digital oscilloscope. The output of the high-voltage square wave pulse power supply is electrically connected to both the synchronization control circuit and the electrothermal coupling test unit. The synchronization control circuit is connected to the external trigger channel of the digital oscilloscope. The output of the electrothermal coupling test unit is connected to the digital oscilloscope via the broadband signal amplifier.

[0058] The high-voltage square wave pulse power supply is used to generate periodic high-voltage square wave pulses with adjustable voltage amplitude, repetition frequency, and edge time to simulate real working conditions.

[0059] The synchronization control circuit is used to synchronously transmit the high-voltage square wave pulse to the digital oscilloscope, triggering the digital oscilloscope to accurately capture the edge of the square wave pulse, so that the acquisition window of the digital oscilloscope is precisely aligned with the pulse edge.

[0060] The electrothermal coupling test unit is used to place the insulating encapsulation material sample 4 to be tested, and input a high-voltage square wave pulse from a high-voltage square wave pulse power supply to test the insulating encapsulation material sample 4, obtain the acoustic signal of molecular vibration of the insulating encapsulation material sample 4 to be tested, and convert it into an electrical signal.

[0061] The broadband signal amplifier is used to amplify the electrical signal output by the electrothermal coupling test unit and transmit it to a digital oscilloscope for signal acquisition.

[0062] Digital oscilloscopes are used to capture and store the original vibration waveform based on the electrical signal of the key phase window at the edge of the square wave pulse.

[0063] In this embodiment, the electrothermal coupling test unit uses an aluminum lower electrode 2 and a copper cylindrical upper electrode 1 to define the test cavity. The insulating encapsulation material sample 4 to be tested is filled between the upper and lower test electrodes. Silicone oil is coated at the interface to reduce sound transmission loss. A semiconductive dielectric layer is laid between the upper electrode 1 and the sample to optimize the electric field distribution. A ceramic insulated heating coil 5 and a temperature monitoring module are configured in the cavity to simulate an ambient temperature of -40℃ to 150℃. The lower electrode 2 is coupled to a PVDF piezoelectric sensor, which can realize the conversion of sound signal to electrical signal.

[0064] Based on the above-mentioned insulation encapsulation material degradation detection system, such as Figure 1 As shown in the figure, this embodiment provides a method for detecting the degradation of insulating packaging materials based on molecular vibrations. The specific implementation steps of the method are as follows:

[0065] S1. Apply a periodic high-voltage square wave pulse voltage simulating the actual operating conditions of a high-voltage power device to the insulating encapsulation material under test, and generate a trigger signal that is precisely synchronized with the rising or falling edge of the periodic high-voltage square wave pulse voltage.

[0066] The test sample 4 of the insulating encapsulation material is placed between the test electrodes of the electrothermal coupling test unit, and the periodic high-voltage square wave pulse voltage, which is the same as the actual operating condition of the high-voltage power device, is simulated by a high-voltage square wave pulse power supply.

[0067] The high-voltage square wave pulse power supply applies a high-voltage square wave pulse voltage to the insulating encapsulation material sample 4 under test by electrically connecting the high-voltage electrode of the electrothermal coupling test unit.

[0068] Simultaneously, based on the output signal of the high-voltage square wave pulse power supply, a trigger signal that is precisely synchronized with the edge of the periodic high-voltage square wave pulse voltage is generated through the synchronization control circuit. This trigger signal is then transmitted to the digital oscilloscope by the synchronization control circuit to trigger the digital oscilloscope to acquire signals.

[0069] S2. Based on the edge effect of high voltage square wave pulse voltage, the sensor detects the molecular vibration acoustic wave signal excited by the internal charge of the insulating packaging material under test driven by the transient electric field force, and converts the molecular vibration acoustic wave signal into an electrical signal.

[0070] S3. Based on the synchronous trigger signal, the converted electrical signal is synchronously acquired to capture the transient molecular vibration waveform within a specific acquisition window after the pulse edge.

[0071] S4. Perform multi-dimensional feature extraction on the acquired transient molecular vibration waveform to obtain the time-domain amplitude features, waveform morphology features, relaxation time feature constants, and wavelet packet entropy of the vibration waveform;

[0072] The time-domain amplitude characteristics include the peak value A of the vibration waveform. pWith effective value A rms By extracting the peak value of the vibration waveform With effective value Its magnitude directly reflects the intensity of the forced motion of the charge at the edge moment, and the peak value A p It is proportional to the square of the pulse voltage amplitude.

[0073] The waveform morphology features include the number of peaks and the time domain width of the vibration waveform. Based on the waveform morphology features, the relationship between the number of peaks and the time domain width can be determined. For example, silicone gel exhibits a double peak under fast edge (50 ns) excitation and turns into a single peak under slow edge (400 ns), while silicone rubber always has a single peak. This morphological difference is directly related to the degree of crosslinking of the material and the degree of freedom of chain segment movement.

[0074] The relaxation time constant was extracted using Prony series fitting. t The relaxation time constant t It can reflect the rigidity of the insulating encapsulation material.

[0075] The vibration signal is decomposed into multiple scales based on wavelet packet decomposition, and then the wavelet packet entropy Sw is determined after quantization decomposition using information entropy. The wavelet packet entropy Sw reflects the degree of accumulation of internal structural defects in the material. The specific method for obtaining the wavelet packet entropy is as follows:

[0076] The raw molecular vibration signal acquired in the window after the pulse edge is preprocessed, and the preprocessed vibration signal is decomposed into N-level wavelet packets to obtain 2 N The wavelet packet decomposition coefficients of each frequency band, where N is an integer not less than 3;

[0077] Calculate the energy E of each frequency band decomposition coefficient. i i=1,2,…,2 N And calculate the total signal energy. ;

[0078] Calculate the energy probability distribution of each frequency band based on the total signal energy. ;

[0079] The wavelet packet entropy is calculated using the information entropy formula, which is:

[0080]

[0081] Among them, an increase in the wavelet packet entropy Sw value indicates an increase in the disorder of the internal structure of the material and a deeper degree of degradation.

[0082] Furthermore, S4 also includes edge time normalization correction based on molecular vibration amplitude, specifically as follows:

[0083] Based on molecular vibration amplitude A and pulse edge time tr Based on the empirical relationship model, a normalized correction formula for the pulse edge time and the standard reference edge time is established.

[0084] The empirical relationship model is as follows:

[0085]

[0086] Wherein, α is the material-related attenuation index calibrated experimentally;

[0087] The normalization correction formula is as follows:

[0088]

[0089] Among them, A p Indicates the measured vibration amplitude; A norm Indicates the equivalent amplitude; t r Indicates the pulse edge time; t ref Indicates the standard reference edge time;

[0090] The actual measurement will be performed at different edge times t. r The vibration amplitude A below p Normalized to standard reference edge time t ref The equivalent amplitude A below norm This is to eliminate the interference caused by different excitation pulse edge rates on the degradation assessment.

[0091] S5. Input the multi-dimensional features of the extracted transient molecular vibration waveform into the pre-built evaluation model or compare it with the preset threshold, and output the qualitative judgment of the current degree of degradation or degradation trend of the insulating packaging material under test, or the degradation evaluation result.

[0092] The extracted multi-dimensional features are compared with a preset threshold. The specific operation is as follows:

[0093] S501. Assess the risk of bond fracture based on the time-domain amplitude characteristics of the vibration waveform as a mechanical failure criterion.

[0094] The extracted time-domain amplitude features are normalized to obtain the equivalent amplitude A of the molecular vibration peak signal. norm By combining the sensitivity S of the piezoelectric sensor 3 with the acoustic impedance characteristics of the insulating encapsulation material, the equivalent alternating stress amplitude σ acting on the molecular chain is calculated. vib According to the equivalent alternating stress amplitude σ vib Determine the equivalent displacement d' of bonding atoms caused by the electric field force pulling the charge;

[0095] The calculated equivalent displacement d' is compared with the critical breaking distance d of the chemical bond of the insulating encapsulation material under test. If d'≥d, the insulating encapsulation material under test is in a high-risk deterioration state, indicating that the molecular vibration generated by a single pulse edge excitation has the mechanical conditions to break the chemical bond.

[0096] The bond fracture risk coefficient R is obtained from the ratio of the equivalent displacement d' to the critical failure distance d. f When R f If R ≥ 1, a degradation risk warning will be issued; if R f If the value is greater than 1 and continues to increase, the insulating encapsulation material is in a state of accelerated deterioration.

[0097] S502. Based on the equivalent alternating stress amplitude and the relaxation time characteristic constant of the vibration waveform determined by the mechanical failure criterion, the aging rate is evaluated according to the energy dissociation criterion.

[0098] The equivalent alternating stress amplitude σ vib Substituting the applied stress σ into the formula for bond fracture frequency:

[0099]

[0100] in, h The bond breaking frequency; n 0 represents the atomic thermal vibration frequency. U 0 represents the dissociation energy under no stress. β For material constants, k Boltzmann's constant, T For testing temperature.

[0101] Define aging acceleration factors A f The bond breakage frequency under the current stress state h Bond breakage frequency under stress-free conditions h 0 The ratio;

[0102]

[0103]

[0104] The aging accelerating factor A f It directly quantifies the degree to which molecular vibrations accelerate the aging rate of materials. A f A higher value indicates that the insulating encapsulation material ages chemically under electromechanical stress more rapidly.

[0105] If aging acceleration factor A f Increase and relax time characteristic constant tIf the growth is synchronous, it is determined that the insulating encapsulation material under test is in a state of accelerated deterioration.

[0106] S503. Quantitatively assess the degradation state of the insulating encapsulation material under test based on dual physical criteria of mechanical failure and energy dissociation, including:

[0107] If only the mechanical failure criterion R f If the value occasionally approaches 1, it indicates that the material has experienced instantaneous overstress, but has not aged.

[0108] If the energy dissociation criterion A f The characteristic constant of continuously increasing relaxation time t Synchronous growth indicates that the insulating encapsulation material under test is in a state of accelerated deterioration.

[0109] If R f ≥1 and A f Enlarge t The simultaneous occurrence of growth indicates that the insulating encapsulation material is at risk of bond breakage, and the aging process has accelerated across the board, indicating severe deterioration or nearing insulation failure.

[0110] Simultaneously, S5 can input the multidimensional features of extracted transient molecular vibrations into a pre-constructed evaluation model, which uses the insulation health index IHI, the formula of which is:

[0111]

[0112] In the formula, w1, w2, and w3 represent weighting coefficients, respectively; A norm Indicates the equivalent amplitude; t is the relaxation time characteristic constant; Sw is the wavelet packet entropy.

[0113] When the Insulation Health Index (IHI) exceeds the preset material property threshold, the insulation encapsulation material under test is determined to be in a state of accelerated deterioration.

Claims

1. A method for detecting the degradation of insulating encapsulation materials based on molecular vibrations, characterized in that, include: S1. Apply a periodic high-voltage square wave pulse voltage simulating the actual operating conditions of a high-voltage power device to the insulating encapsulation material under test, and generate a trigger signal that is precisely synchronized with the rising or falling edge of the periodic high-voltage square wave pulse voltage. S2. Based on the edge effect of high voltage square wave pulse voltage, the sensor detects the molecular vibration acoustic wave signal excited by the internal charge of the insulating packaging material under test driven by the transient electric field force, and converts the molecular vibration acoustic wave signal into an electrical signal. S3. Based on the synchronous trigger signal, the converted electrical signal is synchronously acquired to capture the transient molecular vibration waveform within a specific acquisition window after the pulse edge. S4. Perform multi-dimensional feature extraction on the acquired transient molecular vibration waveform to obtain the time-domain amplitude features, waveform morphology features, relaxation time feature constants, and wavelet packet entropy of the vibration waveform; The specific method for obtaining the wavelet packet entropy of the vibration waveform is as follows: The raw molecular vibration signal acquired in the window after the pulse edge is preprocessed, and the preprocessed vibration signal is decomposed into N-level wavelet packets to obtain 2 N The wavelet packet decomposition coefficients of each frequency band, where N is an integer not less than 3; Calculate the energy Ei of each frequency band decomposition coefficient, i=1,2,…,2 N And calculate the total signal energy. ; Calculate the energy probability distribution of each frequency band based on the total signal energy. ; The wavelet packet entropy is calculated using the information entropy formula, which is: ； S5. Input the multi-dimensional features of the extracted transient molecular vibration waveform into the pre-built evaluation model or compare it with the preset threshold, and output the qualitative judgment of the current degree of degradation or degradation trend of the insulating packaging material under test, or the degradation evaluation result. The assessment model uses the Insulation Health Index (IHI), and its formula is as follows: In the formula, w1, w2, and w3 represent weighting coefficients, respectively; A norm Indicates the equivalent amplitude; τ The characteristic constant of the relaxation time; S w Let be the wavelet packet entropy.

2. The method for detecting the degradation of insulating packaging materials based on molecular vibrations according to claim 1, characterized in that, The specific operation of comparing the extracted multi-dimensional features with a preset threshold as described in S5 is as follows: Key fracture risk assessment based on time-domain amplitude characteristics of vibration waveform; Based on the equivalent alternating stress amplitude determined by the mechanical failure criterion and the relaxation time characteristic constant of the vibration waveform, the aging rate is evaluated according to the energy dissociation criterion. The degradation state of the insulating encapsulation material under test is quantitatively assessed based on both mechanical failure criteria and energy dissociation criteria.

3. The method for detecting the degradation of insulating packaging materials based on molecular vibrations according to claim 2, characterized in that, The key fracture risk assessment based on the time-domain amplitude characteristics of the vibration waveform as a mechanical failure criterion includes: The extracted time-domain amplitude features are normalized to obtain the equivalent amplitude A of the molecular vibration peak signal. norm By combining the sensitivity S of the piezoelectric sensor with the acoustic impedance characteristics of the insulating encapsulation material, the equivalent alternating stress amplitude σ acting on the molecular chain is calculated. vib According to the equivalent alternating stress amplitude σ vib Determine the equivalent displacement d' of bonding atoms caused by the electric field force pulling the charge; The calculated equivalent displacement d' is compared with the critical breaking distance d of the chemical bonds of the insulating encapsulation material to be tested. If d' ≥ d, the insulating encapsulation material to be tested is in a high-risk deterioration state. The bond fracture risk coefficient R is obtained from the ratio of the equivalent displacement d' to the critical failure distance d. f When R f If R ≥ 1, a degradation risk warning will be issued; if R f If the value is greater than 1 and continues to increase, the insulating encapsulation material is in a state of accelerated deterioration.

4. The method for detecting the degradation of insulating packaging materials based on molecular vibrations according to claim 2, characterized in that, The aging rate assessment based on the energy dissociation criterion includes: The equivalent alternating stress amplitude σ vib Substituting the applied stress σ into the formula for bond fracture frequency: in, h The bond breaking frequency; ν 0 represents the atomic thermal vibration frequency. U 0 represents the dissociation energy under no stress. β For material constants, k Boltzmann's constant, T For testing temperature; Define aging acceleration factors A f The bond breakage frequency under the current stress state h Bond fracture frequency under stress-free conditions h 0 The ratio; If aging acceleration factor A f Increase and relax time characteristic constant τ If the growth is synchronous, it is determined that the insulating encapsulation material under test is in a state of accelerated deterioration.

5. The method for detecting the degradation of insulating packaging materials based on molecular vibrations according to claim 1, characterized in that, S4 extracts the relaxation time constant using Prony series fitting. τ .

6. The method for detecting the degradation of insulating packaging materials based on molecular vibrations according to claim 1, characterized in that, S4 also includes edge time normalization correction based on molecular vibration amplitude, specifically: Based on molecular vibration amplitude A and pulse edge time t r Based on the empirical relationship model, the normalized correction formula for the pulse edge time and the standard reference edge time is established as follows: Among them, A p Indicates the measured vibration amplitude; A norm Indicates the equivalent amplitude; t r Indicates the pulse edge time; t ref Indicates the standard reference edge time; The actual measurement will be performed at different edge times t. r The vibration amplitude A below p Normalized to standard reference edge time t ref The equivalent amplitude A below norm .

7. A molecular vibration-based insulation packaging material degradation detection system for implementing the molecular vibration-based insulation packaging material degradation detection method of claim 1, characterized in that, It includes a high-voltage square wave pulse power supply, a synchronous control circuit, an electrothermal coupling test unit, a broadband signal amplifier, and a digital oscilloscope; the output terminal of the high-voltage square wave pulse power supply is electrically connected to the synchronous control circuit and the electrothermal coupling test unit respectively, and the synchronous control circuit is connected to the external trigger channel of the digital oscilloscope. The output of the electrothermal coupling test unit is connected to a digital oscilloscope via a broadband signal amplifier. The high-voltage square wave pulse power supply is used to generate periodic high-voltage square wave pulses with adjustable voltage amplitude, repetition frequency and edge time to simulate real working conditions. The synchronization control circuit is used to synchronously transmit the high-voltage square wave pulse to the digital oscilloscope, triggering the digital oscilloscope to accurately capture the edge of the square wave pulse, so that the acquisition window of the digital oscilloscope is precisely aligned with the pulse edge. The electrothermal coupling test unit is used to place the insulating encapsulation material sample to be tested, and input a high-voltage square wave pulse from a high-voltage square wave pulse power supply to test the insulating encapsulation material sample, obtain the acoustic signal of molecular vibration of the insulating encapsulation material sample to be tested, and convert it into an electrical signal. A broadband signal amplifier is used to amplify the electrical signal output by the electrothermal coupling test unit and transmit it to a digital oscilloscope for signal acquisition. Digital oscilloscopes are used to capture and store the original vibration waveform based on the electrical signal of the key phase window at the edge of the square wave pulse.

8. The molecular vibration-based insulation packaging material degradation detection system according to claim 7, characterized in that, The electrothermal coupling test unit uses an aluminum lower electrode and a copper cylindrical upper electrode to define the test cavity. The insulating encapsulation material sample to be tested is filled between the upper and lower test electrodes. The interface is coated with silicone oil to reduce sound transmission loss. A semiconducting dielectric layer is laid between the upper electrode and the sample to optimize the electric field distribution. A ceramic insulated heating coil and a temperature monitoring module are configured inside the cavity. The lower electrode is coupled with a PVDF piezoelectric sensor.

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