Dielectric parameter evaluation method and related device for nonlinear conductive composite insulation materials

Abstract

The present invention belongs to the field of high-power power electronic device insulation and discloses a method and related apparatus for evaluating the dielectric parameters of nonlinear conductive composite insulating materials. The method comprises: obtaining the field strength, time, temperature, and frequency of an applied voltage; and evaluating the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material based on the field strength, time, temperature, and frequency of the applied voltage according to a preset spatiotemporal coupling model. When constructing the spatiotemporal coupling model, an exponential model is first constructed that relates filler orientation to the field strength and time of the applied voltage. Based on this model, a correlation model is established between the material's dielectric relaxation process and the material's dielectric constant, dielectric loss, filler orientation, applied voltage frequency, and temperature. Finally, the relationship between the material's conductivity, orientation, and temperature is established by considering the hopping conductivity behavior of electrons in the material at high field strengths. Based on this spatiotemporal coupling model, the dielectric parameters of the nonlinear conductive composite insulating material can be accurately evaluated.

Description

Technical Field

[0001] The invention belongs to the field of high-power power electronic device insulation and relates to a dielectric parameter evaluation method for a nonlinear conductive composite insulating material and a related device. Background Art

[0002] Building high-speed, high-reliability, and high-efficiency energy conversion equipment centered around high-voltage, high-power insulated gate bipolar transistors (IGBTs) is key to transforming "rough electricity" into "fine electricity." Silicone elastomers (SEs) are widely used as the insulating material for IGBT packaging due to their excellent electrical, mechanical, and thermal properties.

[0003] However, with the increasing voltage and miniaturization of IGBTs, localized field distortion caused by dielectric parameter mismatches at the internal three-junction junction has become increasingly serious. When the field strength exceeds a certain threshold, electrical dendrites and localized discharges can form between the silicone elastomer and the substrate surface. In severe cases, this can even damage the device and trigger large-scale power outages. Therefore, effectively optimizing the device's electric field distribution characteristics is crucial for safe and stable system operation.

[0004] In recent years, nonlinear conductive composite insulating materials have been shown to effectively suppress local electric field distortion in IGBTs due to their flexible field intensity control methods. In situ electric field-induced filler self-assembly is an advanced material preparation technology. This technology uses the force of the electric field to guide the orderly arrangement of filler particles in the matrix, thereby optimizing the material's performance. It is an efficient field intensity optimization method. However, during the in situ electric field-assisted preparation process, the nonlinear parameters of the material are functions of time and space. In order to obtain the ideal parameter distribution state and maximize the optimization of the electric field, precise control of process parameters is required. These parameters (including ambient temperature, filler orientation, and time) are strongly coupled with each other and are related to the structural shape. Therefore, they are difficult to measure experimentally, and the performance of nonlinear conductive composite insulating materials cannot be effectively perceived. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for evaluating the dielectric parameters of a nonlinear conductive composite insulating material and a related device.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for evaluating dielectric parameters of a nonlinear conductive composite insulating material, comprising: obtaining the field strength, time, temperature, and frequency of an applied voltage; and evaluating the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material according to a preset spatiotemporal coupling model based on the field strength, time, temperature, and frequency of the applied voltage. The spatiotemporal coupling model is obtained by constructing an exponential model of filler orientation with the field strength and time of the applied voltage; establishing a first correlation model for the relationship between the dielectric constant of the nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature based on a dielectric relaxation process, and establishing a second correlation model for the relationship between the dielectric loss of the nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature; establishing a third correlation model for the relationship between the conductivity of the nonlinear conductive composite insulating material and the filler orientation and temperature based on the hopping conductivity behavior of electrons in the nonlinear conductive composite insulating material at high field strengths; and substituting the exponential model of the filler orientation with the field strength and time of the applied voltage into the first, second, and third correlation models and combining them to obtain the spatiotemporal coupling model.

[0008] Optionally, constructing an exponential model of the degree of filler orientation and the applied voltage field intensity and time includes: using the normalized amplitude of the current change during the filler orientation process as a quantitative indicator to characterize the degree of filler orientation D, and considering the relaxation time constant τ required for complete particle orientation, fitting the normalized current change curve by the following formula to obtain the relationship D(E,t) between D and the applied voltage field intensity E and time t:

[0009]

[0010] Where a1 is the normalized current steady-state value, a2 is the normalized current initial value;

[0011] By fitting the normalized curve of current change, the relationship between τ and E is obtained as follows:

[0012] τ=a3exp(-a4E)

[0013] According to the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed:

[0014]

[0015] Among them, a3 and a4 are fitting parameters.

[0016] Optionally, the first correlation model for establishing the relationship between the dielectric constant of the nonlinear conductive composite insulating material and the filler orientation degree, the frequency of the applied voltage, and the temperature includes:

[0017] Based on the test TSDC current ITSDC Determine the potential barrier height H of nonlinear conductive composite insulating materials:

[0018]

[0019] The nonlinear correlation model between the barrier height H and filler orientation degree D is constructed by the following formula:

[0020]

[0021] The expression of the dipole polarization dielectric constant is derived based on the molecular motion barrier energy level and the Ker-Mo equation:

[0022]

[0023]

[0024] Further transformation of the above formula can be obtained:

[0025]

[0026] Construct the first correlation model of the following formula:

[0027]

[0028] Where p0 is the polarization intensity of the charge after freezing; τ0 is the intrinsic relaxation time of the charge, which satisfies the quantitative relationship τ0 = π / ω0, ω0 is the frequency of the applied voltage at the intrinsic angle of thermal motion of the charge in the potential barrier; T is the temperature; T0 is the lowest temperature of the sample when heating begins in the TSDC test; k is the Boltzmann constant; ω is the frequency of the applied voltage at the alternating electric field angle; ε s is the static dielectric constant; ε ∞ is the optical frequency dielectric constant; τ D is the relaxation polarization time; ν is the frequency of the applied voltage for the thermal vibration of the molecule in equilibrium; a5, a6, a8, a9 and a 10 are fitting parameters; ε′ is the dielectric constant.

[0029] Optionally, the second correlation model for establishing the relationship between the dielectric loss of the nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature includes:

[0030] The expression of the dielectric loss of dipole polarization is derived based on the molecular motion barrier energy level and the Ker-Mo equation:

[0031]

[0032] Further transformation of the above formula can be obtained:

[0033]

[0034] Construct the following second correlation model:

[0035]

[0036] Where, ε″ is the dielectric loss; a 11 is the fitting parameter.

[0037] Optionally, the third correlation model for establishing the relationship between the electrical conductivity of the nonlinear conductive composite insulating material, the filler orientation, and the temperature includes:

[0038] The relationship between the current density formed by carrier migration through hopping conduction and the external electric field strength is:

[0039] J(D,T)=A(D,T)·sinh(B(D,T)·E w )

[0040]

[0041] B(D,T)=eR(D,T) / 2kT

[0042] Among them, E w is the external electric field strength, n is the carrier concentration, e is the basic charge, R is the average jump distance, ν is the frequency of charge escape applied voltage, E hop is the average jump activation energy, E A is the acceptor energy level of the filler; J(D,T) is the current density; A(D,T) is the jump conduction current; B(D,T) is the intermediate process parameter;

[0043] Based on the above formula, the corresponding solution model is established:

[0044]

[0045] R(D,T)=S2(T)P(D)

[0046] α(T)=S1(T) / S2(T)

[0047] Further we get:

[0048]

[0049] Convert to third-association model:

[0050]

[0051] Where P(D) = -b1D 3 +b2D 2 -b3D+b4, S2(T)=-b5T 2+b6T-b7,α(T)=2eνn(T)=b8T 2 -b9T+b 10 , M(D)=b 11 D 2 +b 12 D+b 13 ; P(D), S2(T), α(T) and M(D) are all process parameters during fitting; b1 to b 13 are all fitting parameters.

[0052] In a second aspect, the present invention provides a dielectric parameter evaluation system for a nonlinear conductive composite insulating material, comprising: a data acquisition module for acquiring the field strength, time, temperature, and frequency of an applied voltage; a parameter evaluation module for evaluating the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material based on the field strength, time, temperature, and frequency of the applied voltage according to a preset spatiotemporal coupling model; wherein the spatiotemporal coupling model is obtained by: constructing an exponential model of filler orientation with the field strength and time of the applied voltage; establishing a dielectric constant of the nonlinear conductive composite insulating material based on a dielectric relaxation process; The first correlation model of the relationship between the dielectric constant and the filler orientation, the frequency of the applied voltage and the temperature is used to establish a second correlation model of the relationship between the dielectric loss of the nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage and the temperature; based on the jumping conductivity behavior of electrons in the nonlinear conductive composite insulating material at high field strength, a third correlation model of the relationship between the conductivity of the nonlinear conductive composite insulating material and the filler orientation and temperature is established; the exponential model of the filler orientation, the applied voltage field strength and time is substituted into the first correlation model, the second correlation model and the third correlation model and combined to obtain a spatiotemporal coupling model.

[0053] Optionally, constructing an exponential model of filler orientation, field intensity, and time of applied voltage includes:

[0054] The normalized amplitude of the current change during the filler orientation process is used as a quantitative indicator to characterize the filler orientation degree D. Based on the relaxation time constant τ required for complete particle orientation, the normalized current change curve is fitted using the following formula to obtain the relationship D with the applied voltage field intensity E and time t: D(E,t):

[0055]

[0056] Where a1 is the normalized current steady-state value, a2 is the normalized current initial value;

[0057] By fitting the normalized curve of current change, the relationship between τ and E is obtained as follows:

[0058] τ=a3exp(-a4E)

[0059] According to the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed:

[0060]

[0061] Among them, a3 and a4 are fitting parameters.

[0062] Optionally, a space-time coupling model construction module is also included for constructing a space-time coupling model.

[0063] In a third aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the above-mentioned method for evaluating dielectric parameters of nonlinear conductive composite insulating materials are implemented.

[0064] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for evaluating dielectric parameters of nonlinear conductive composite insulating materials.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The present invention proposes a method for evaluating the dielectric parameters of nonlinear conductive composite insulating materials. This method uses a pre-defined spatiotemporal coupling model to evaluate the dielectric constant, dielectric loss, and conductivity of nonlinear conductive composite insulating materials based on the applied voltage intensity, duration, temperature, and frequency. By constructing an exponential model that correlates filler orientation with the applied voltage intensity and duration, it accurately describes the variation in orientation, providing theoretical guidance for analyzing the dynamics of filler particles under electric field assistance. Compared to empirical formula fitting methods, the constructed spatiotemporal coupling model, based on the dielectric relaxation process and jump conductance principle of the material, has clear physical significance, ensuring the accuracy and precision of the model and enabling accurate evaluation of the dielectric parameters of nonlinear conductive composite insulating materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a flow chart of a method for evaluating dielectric parameters of a nonlinear conductive composite insulating material according to an embodiment of the present invention.

[0068] Figure 2 Schematic diagram of a normalized current curve according to an embodiment of the present invention.

[0069] Figure 3 1 is a graph showing a change in dielectric constant at different temperatures according to an embodiment of the present invention; wherein, FIG (a), FIG (b) and FIG (c) respectively represent the change in dielectric constant at 30°C, 60°C and 90°C.

[0070] Figure 4 1 is a graph showing the change in dielectric loss at different temperatures according to an embodiment of the present invention; wherein, FIG (a), FIG (b) and FIG (c) represent the change in dielectric loss at 30°C, 60°C and 90°C, respectively.

[0071] Figure 5 1 is a graph showing the change in conductivity at different temperatures according to an embodiment of the present invention; wherein, FIG (a), FIG (b) and FIG (c) respectively represent the change in conductivity at 30°C, 60°C and 90°C.

[0072] Figure 6 This is a block diagram of a dielectric parameter evaluation system for nonlinear conductive composite insulating materials according to an embodiment of the present invention. DETAILED DESCRIPTION

[0073] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0074] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0075] The present invention is described in further detail below with reference to the accompanying drawings:

[0076] See also Figure 1 In one embodiment of the present invention, a method for evaluating the dielectric parameters of nonlinear conductive composite insulating materials is provided. The method is based on a spatiotemporal evolution model of nonlinear conductive composite insulating materials. Specifically, the method considers the dielectric relaxation process and carrier hopping conductivity process of nonlinear conductive composite insulating materials to determine a correlation model between filler orientation and temperature and dielectric parameters. The method can be used to evaluate the dielectric parameters of composite insulating materials in high-voltage power modules.

[0077] Specifically, the dielectric parameter evaluation method of the nonlinear conductive composite insulating material of the present invention comprises the following steps:

[0078] S1: Obtain the field strength, time, temperature and frequency of the applied voltage.

[0079] Based on the applied voltage field intensity, time, temperature, and frequency, the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material are evaluated according to a preset spatiotemporal coupling model.

[0080] The space-time coupling model is obtained as follows:

[0081] Construct an exponential model of the relationship between filler orientation and applied voltage intensity and time;

[0082] Based on the dielectric relaxation process, a first correlation model is established for the relationship between the dielectric constant of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature. A second correlation model is established for the relationship between the dielectric loss of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature.

[0083] Based on the hopping conductivity behavior of electrons in nonlinear conductive composite insulating materials at high field strength, a third correlation model is established to explain the relationship between the conductivity of nonlinear conductive composite insulating materials, filler orientation, and temperature.

[0084] The exponential model of filler orientation, applied voltage field intensity and time is substituted into the first correlation model, the second correlation model and the third correlation model and combined to obtain a spatiotemporal coupling model.

[0085] The present invention proposes a method for evaluating the dielectric parameters of nonlinear conductive composite insulating materials. This method uses a pre-defined spatiotemporal coupling model to evaluate the dielectric constant, dielectric loss, and conductivity of nonlinear conductive composite insulating materials based on the applied voltage intensity, duration, temperature, and frequency. By constructing an exponential model that correlates filler orientation with the applied voltage intensity and duration, it accurately describes the variation in orientation, providing theoretical guidance for analyzing the dynamics of filler particles under electric field assistance. Compared to empirical formula fitting methods, the constructed spatiotemporal coupling model, based on the dielectric relaxation process and jump conductance principle of the material, has clear physical significance, ensuring the accuracy and precision of the model and enabling accurate evaluation of the dielectric parameters of nonlinear conductive composite insulating materials.

[0086] In one possible embodiment, the exponential model of the filler orientation degree and the applied voltage field strength and time is constructed, which includes: using the normalized amplitude of the current change during the filler orientation process as a quantitative indicator to characterize the filler orientation degree D, and on the basis of considering the relaxation time constant τ required for complete orientation of the particles, constructing a single exponential model of the filler orientation degree D and the applied voltage field strength E and the relaxation time constant τ, and then further constructing an exponential model of the filler orientation degree and the applied voltage field strength and time.

[0087] Specifically, the current curve measured during the filler orientation process is first normalized, and the normalized amplitude of the current change during the filler orientation process is used as a quantitative indicator to characterize the filler orientation degree D. On the basis of considering the relaxation time constant τ required for complete particle orientation, the normalized current change curve is fitted using the following formula to obtain the relationship D (E, t) between D, the applied voltage field intensity E, and the time t:

[0088]

[0089] Among them, a1 is the normalized current steady-state value, a2 is the normalized current initial value, so a1=a2=1.

[0090] Then, the current normalized curve can be used to solve the τ under different field strengths.

[0091] Then, the current normalized curve is fitted, and the relationship between τ and E can be obtained as follows:

[0092] τ=a3exp(-a4E)

[0093] Finally, based on the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed:

[0094]

[0095] Among them, a3 and a4 are fitting parameters, which are determined during the fitting process and are both constants.

[0096] In one possible implementation, a quantitative correlation model between the barrier energy level H and the filler orientation degree D was first determined. Furthermore, considering the dielectric relaxation process of nonlinear conductive composite insulating materials, the relationships between the dielectric constant ε′ and dielectric loss ε″ and the barrier energy level H, the applied voltage frequency f, and the temperature T were established.

[0097] Applying voltage to a nonlinear conductive composite insulating material for the same duration at different electric field intensities will induce different filler orientation degrees D in the filler. The filler orientation degree D affects the overall barrier energy level H of the nonlinear conductive composite insulating material, thereby affecting the dielectric constant and conductivity.

[0098] Therefore, in this embodiment, firstly based on the TSDC current I TSDC Determine the potential barrier height H of nonlinear conductive composite insulating materials:

[0099]

[0100] Where p0 is the polarization intensity of the charge after freezing / C·m -2 ; τ0 is the intrinsic relaxation time of the charge / s, which satisfies the quantitative relationship τ0=π / ω0, ω0 refers to the frequency of the applied voltage at the intrinsic angle of thermal motion of the charge in the potential barrier, and T is the temperature; T0 is the lowest temperature of the sample when the TSDC test starts heating, and k is the Boltzmann constant.

[0101] On this basis, a nonlinear correlation model of barrier height H and filler orientation degree D can be constructed:

[0102]

[0103] In addition, since polar dielectric molecules have a certain inherent dipole moment, when subjected to an electric field, the dielectric rotates in a directional manner under the action of the electric field, generating an induced electric moment and a residual electric moment. This phenomenon is called dipole polarization. Based on the molecular motion barrier energy level and the Ker-Mer equation, the expressions for the dielectric constant and dielectric loss tangent of dipole polarization can be derived as follows:

[0104]

[0105]

[0106]

[0107] Where ω is the frequency of the voltage applied by the alternating electric field; ε s is the static dielectric constant; ε ∞ is the optical frequency dielectric constant; τ D is the polarization time of relaxation; ν is the frequency of the applied voltage for thermal vibration of the molecule in equilibrium; a5, a6, a8, a9, a 10 and a 11 All of them are fitting parameters, determined during the fitting process, and are constants; ε′ is the dielectric constant, and ε″ is the dielectric loss.

[0108] It can be found that the formula naturally takes into account the effects of the frequency f of the applied voltage, the temperature T, and the degree of orientation D of the filler (through the molecular barrier H).

[0109] Therefore, we can use only the classical formula for modeling, and further transform the above formula to obtain:

[0110]

[0111]

[0112] Finally, the first correlation model between the dielectric constant of nonlinear conductive composite insulation materials and the filler orientation, the frequency of the applied voltage, and the temperature can be constructed:

[0113]

[0114] And the second correlation model between the dielectric loss of nonlinear conductive composite insulation materials and the filler orientation, the frequency of the applied voltage and the temperature:

[0115]

[0116] In a possible embodiment, based on the consideration of the hopping conductivity behavior of electrons in the nonlinear conductive composite insulating material at high field strength, the relationship between the conductivity σ of the nonlinear conductive composite insulating material and the filler orientation degree D and the temperature T is established.

[0117] Since the energy bands formed by the periodic arrangement of atoms can only exist in local areas, the energy bands are discontinuous in areas with irregular atomic distribution. In areas with amorphous structures, electrons cannot move freely like in the conduction bands of crystals. Electrons need to overcome the corresponding potential barriers to migrate from the conduction band of a small crystal area to the conduction band of an adjacent small crystal area. When the electric field strength is not strong (the field strength is less than the switching field strength E b When the electrons in the conduction band of the local energy band jump over the potential barrier to the adjacent microcrystalline band under the action of thermal vibration, thus forming electron hopping conductivity.

[0118] Specifically, the relationship between the current density formed by carrier migration through hopping conduction and the external electric field strength is:

[0119] J(D,T)=A(D,T)·sinh(B(D,T)·E w )

[0120]

[0121] B(D,T)=eR(D,T) / 2kT

[0122] Among them, E w is the external electric field strength, n is the carrier concentration, and e is the basic charge 1.6×10 -19 C, R is the average jump distance (related to filler orientation D and temperature T), ν is the frequency of charge escape applied voltage, E hop is the average jump activation energy (related to filler orientation D), E Ais the acceptor energy level of the filler; J(D,T) is the current density; A(D,T) is the jump conduction current; B(D,T) is the intermediate process parameter.

[0123] In order to obtain the relationship between the electrical conductivity σ and the filler orientation degree D and the temperature T, a corresponding solution model is established based on the above formula in this embodiment:

[0124]

[0125] R(D,T)=S2(T)P(D)

[0126] α(T)=S1(T) / S2(T)

[0127] Further we get:

[0128]

[0129] Then convert it to a third relational model:

[0130]

[0131] In addition, in order to solve the third correlation model, the relevant expressions of P(D), S2(T), α(T) and M(D) are established in this embodiment as follows:

[0132] P(D)=-b1D 3 +b2D 2 -b3D+b4

[0133] S2(T)=-b5T 2 +b6T-b7

[0134] α(T)=2eνn(T)=b8T 2 -b9T+b 10

[0135] M(D)=b 11 D 2 +b 12 D+b 13

[0136] Among them, P(D), S2(T), α(T) and M(D) are the process parameters during fitting; b1 to b 13 They are all fitting parameters, determined during the fitting process, and are all constants.

[0137] Finally, by substituting the relationship between the filler orientation degree D and the applied voltage field strength E and time t into the above-mentioned first correlation model, second correlation model and third correlation model, we can obtain the influence of the dielectric parameters (dielectric constant, dielectric loss and conductivity) of the nonlinear conductive composite insulating material on the applied voltage field strength, time, temperature and applied voltage frequency, that is, the space-time coupling model.

[0138] In a possible implementation, the dielectric parameter evaluation method of the nonlinear conductive composite insulating material of the present invention is described by taking SiCw / SE nonlinear conductive composite insulating material as an example.

[0139] See also Figure 2 During the experiment, the current amplitude of each sample was measured when the filler was oriented under the action of an electric field, and the current curve was normalized to characterize the filler orientation degree D. This resulted in SiCw / SE nonlinear conductive insulating composite materials with filler orientation degrees of 0.256, 0.3274, 0.4522, 0.7127, and 1, respectively, denoted as SwE1 to SwE5. Among them, the pure silicone elastomer is SE. The relationship between the filler orientation degree D, the field strength E, and t was then fitted to obtain the following equation:

[0140] See also Figure 3 and 4 , the experiment obtained the relationship between the dielectric constant and dielectric loss of SiCw / SE nonlinear conductive composite insulating materials and the frequency of applied voltage at different temperatures. It can be found that with the increase of temperature, the ε′ and ε″ of samples with the same filler orientation degree both show a trend of gradual increase. And the increase of ε′ and ε″ in the 30-60℃ stage is significantly greater than that in the 6-90℃ stage. In addition, at the same temperature and applied voltage frequency, with the increase of filler orientation in SiCw / SE nonlinear conductive composite insulating materials, its dielectric constant also gradually increases. From this, the fitting parameters a5, a6, a8, a9, a 10 and a 11 .

[0141] See also Figure 5 , the experiment obtained the relationship between the conductivity of SiCw / SE nonlinear conductive composite insulating materials and the field strength of the applied voltage at different temperatures. It can be found that the change in the conductivity of the material at all temperatures can be divided into two stages. In the low field strength region: when the field strength is lower than the switching field strength, the conductivity hardly changes with the increase of the field strength. In the high field strength region, as the external applied field strength increases and is greater than the switching field strength, the conductivity rises rapidly and enters the nonlinear region. Therefore, based on the experimental parameters, the fitting parameters b1~b in the expressions of P(D), S2(T), α(T) and M(D) can be determined. 13 The specific value of .

[0142] The present invention's dielectric parameter evaluation method for nonlinear conductive composite insulating materials is primarily based on a spatiotemporal coupling model. To construct this model, an exponential model is first constructed that correlates filler orientation with the field intensity and time of the applied voltage. Furthermore, a correlation model is established between the material's dielectric constant and dielectric loss, filler orientation, applied voltage frequency, and temperature, taking into account the material's dielectric relaxation process. Finally, the relationship between the material's conductivity, orientation, and temperature is established by considering the material's electron hopping conductivity at high field strengths.

[0143] The following are device embodiments of the present invention, which can be used to perform the method embodiments of the present invention. For details not disclosed in the device embodiments, please refer to the method embodiments of the present invention.

[0144] See also Figure 6 In another embodiment of the present invention, a nonlinear conductive composite insulating material dielectric parameter evaluation system is provided, which can be used to implement the above-mentioned nonlinear conductive composite insulating material dielectric parameter evaluation method. Specifically, the nonlinear conductive composite insulating material dielectric parameter evaluation system includes a data acquisition module and a parameter evaluation module.

[0145] The data acquisition module is used to obtain the applied voltage field intensity, time, temperature, and frequency; the parameter evaluation module is used to evaluate the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material based on the applied voltage field intensity, time, temperature, and frequency according to a preset spatiotemporal coupling model. The spatiotemporal coupling model is obtained by constructing an exponential model for filler orientation and the applied voltage field intensity and time; establishing a first correlation model for the relationship between the dielectric constant of the nonlinear conductive composite insulating material and the filler orientation, applied voltage frequency, and temperature based on the dielectric relaxation process; establishing a second correlation model for the relationship between the dielectric loss of the nonlinear conductive composite insulating material and the filler orientation, applied voltage frequency, and temperature; establishing a third correlation model for the relationship between the conductivity of the nonlinear conductive composite insulating material and the filler orientation and temperature based on the hopping conductivity behavior of electrons in the nonlinear conductive composite insulating material at high electric field intensity; and substituting the exponential model for the filler orientation and the applied voltage field intensity and time into the first, second, and third correlation models and combining them to obtain the spatiotemporal coupling model.

[0146] In one possible embodiment, constructing an exponential model of the degree of filler orientation and the applied voltage field intensity and time includes: using the normalized amplitude of the current change during the filler orientation process as a quantitative indicator to characterize the degree of filler orientation D, and considering the relaxation time constant τ required for complete particle orientation, fitting the normalized current change curve by the following formula to obtain the relationship D(E,t) between D and the applied voltage field intensity E and time t:

[0147]

[0148] Where a1 is the normalized current steady-state value, and a2 is the normalized current initial value.

[0149] By fitting the normalized curve of current change, the relationship between τ and E is obtained as follows:

[0150] τ=a3 exp(-a4E)

[0151] According to the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed.

[0152]

[0153] Among them, a3 and a4 are fitting parameters.

[0154] In a possible implementation, the dielectric parameter evaluation system for nonlinear conductive composite insulating materials further includes a space-time coupling model construction module for constructing a space-time coupling model.

[0155] All relevant contents of each step involved in the embodiment of the nonlinear conductive composite insulating material dielectric parameter evaluation method can be referred to the functional description of the corresponding functional modules of the nonlinear conductive composite insulating material dielectric parameter evaluation system in the embodiment of the present invention, and will not be repeated here.

[0156] The module division in the embodiments of the present invention is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in various embodiments of the present invention may be integrated into a single processor, exist physically as separate modules, or two or more modules may be integrated into a single module. The integrated modules may be implemented in either hardware or software functional modules.

[0157] In another embodiment of the present invention, a computer device is provided, comprising a processor and a memory, wherein the memory is configured to store a computer program, wherein the computer program includes program instructions, and the processor is configured to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., and is the computing core and control core of the terminal. The processor is adapted to implement one or more instructions, specifically, to load and execute one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function. The processor described in the embodiment of the present invention can be used to operate the dielectric parameter evaluation method of nonlinear conductive composite insulating materials.

[0158] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device, used to store programs and data. It is understood that the computer-readable storage medium herein may include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides storage space, which stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium herein may be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor may load and execute the one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the dielectric parameter evaluation method for nonlinear conductive composite insulating materials described in the above-mentioned embodiment.

[0159] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0160] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0162] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating dielectric parameters of nonlinear conductive composite insulating materials, characterized in that: include: Obtaining the field strength, time, temperature, and frequency of the applied voltage; Based on the applied voltage field intensity, time, temperature and frequency, the dielectric constant, dielectric loss and conductivity of the nonlinear conductive composite insulation material are evaluated according to a preset spatiotemporal coupling model; The space-time coupling model is obtained as follows: Construct an exponential model of the relationship between filler orientation and applied voltage intensity and time; Based on the dielectric relaxation process, a first correlation model is established for the relationship between the dielectric constant of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature. A second correlation model is established for the relationship between the dielectric loss of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature. Based on the hopping conductivity behavior of electrons in nonlinear conductive composite insulating materials at high field strength, a third correlation model is established to explain the relationship between the conductivity of nonlinear conductive composite insulating materials, filler orientation, and temperature. The exponential model of filler orientation, applied voltage field intensity and time is substituted into the first correlation model, the second correlation model and the third correlation model and combined to obtain a spatiotemporal coupling model.

2. The method for evaluating dielectric parameters of nonlinear conductive composite insulating materials according to claim 1, characterized in that: The exponential model of constructing the filler orientation degree and the field intensity and time of the applied voltage includes: The normalized amplitude of the current change during the filler orientation process is used as a quantitative indicator to characterize the filler orientation degree D. Based on the relaxation time constant τ required for complete particle orientation, the normalized current change curve is fitted using the following formula to obtain the relationship D with the applied voltage field intensity E and time t: D(E,t): Where a1 is the normalized current steady-state value, a2 is the normalized current initial value; By fitting the normalized curve of current change, the relationship between τ and E is obtained as follows: τ=a3 exp(-a4E) According to the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed: Among them, a3 and a4 are fitting parameters.

3. The method for evaluating dielectric parameters of nonlinear conductive composite insulating materials according to claim 1, characterized in that: The first correlation model for establishing the relationship between the dielectric constant of the nonlinear conductive composite insulating material and the filler orientation degree, the frequency of the applied voltage, and the temperature includes: Based on the test TSDC current I TSDC Determine the potential barrier height H of nonlinear conductive composite insulating materials: The nonlinear correlation model between the barrier height H and filler orientation degree D is constructed by the following formula: The expression of the dipole polarization dielectric constant is derived based on the molecular motion barrier energy level and the Ker-Mo equation: Further transformation of the above formula can be obtained: Construct the first correlation model of the following formula: Where p0 is the polarization intensity of the charge after freezing; τ0 is the intrinsic relaxation time of the charge, which satisfies the quantitative relationship τ0 = π / ω0, ω0 is the frequency of the applied voltage at the intrinsic angle of thermal motion of the charge in the potential barrier; T is the temperature; T0 is the lowest temperature of the sample when heating begins in the TSDC test; k is the Boltzmann constant; ω is the frequency of the applied voltage at the alternating electric field angle; ε s is the static dielectric constant; ε ∞ is the optical frequency dielectric constant; τ D is the relaxation polarization time; ν is the frequency of the applied voltage for the thermal vibration of the molecule in equilibrium; a5, a6, a8, a9 and a 10 are fitting parameters; ε′ is the dielectric constant.

4. The method for evaluating dielectric parameters of nonlinear conductive composite insulating materials according to claim 3, characterized in that: The second correlation model for establishing the relationship between the dielectric loss of the nonlinear conductive composite insulating material and the filler orientation degree, the frequency of the applied voltage, and the temperature includes: The expression of the dielectric loss of dipole polarization is derived based on the molecular motion barrier energy level and the Ker-Mo equation: Further transformation of the above formula can be obtained: Construct the following second correlation model: Where, ε″ is the dielectric loss; a 11 is the fitting parameter.

5. The method for evaluating dielectric parameters of nonlinear conductive composite insulating materials according to claim 4, characterized in that: The third correlation model for establishing the relationship between the conductivity of the nonlinear conductive composite insulating material, the filler orientation degree, and the temperature includes: The relationship between the current density formed by carrier migration through hopping conduction and the external electric field strength is: J(D,T)=A(D,T)·sinh(B(D,T)·E w ) B(D,T)=eR(D,T) / 2kT Among them, E w is the external electric field strength, n is the carrier concentration, e is the basic charge, R is the average jump distance, ν is the frequency of charge escape applied voltage, E hop is the average jump activation energy, E A is the acceptor energy level of the filler; J(D,T) is the current density; A(D,T) is the jump conduction current; B(D,T) is the intermediate process parameter; Based on the above formula, the corresponding solution model is established: R(D,T)=S2(T)P(D) α(T)=S1(T) / S2(T) Further we get: Convert to third-association model: Where P(D) = -b1D 3 +b2D 2 -b3D+b4, S2(T)=-b5T 2 +b6T-b7,α(T)=2eνn(T)=b8T 2 -b9T+b 10 , M(D)=b 11 D 2 +b 12 D+b 13 ; P(D), S2(T), α(T) and M(D) are all process parameters during fitting; b1 to b 13 are all fitting parameters.

6. A dielectric parameter evaluation system for nonlinear conductive composite insulating materials, characterized in that: include: A data acquisition module is used to obtain the field intensity, time, temperature and frequency of the applied voltage; a parameter evaluation module for evaluating the dielectric constant, dielectric loss, and conductivity of the nonlinear conductive composite insulating material based on the field intensity, time, temperature, and frequency of the applied voltage according to a preset spatiotemporal coupling model; The space-time coupling model is obtained as follows: Construct an exponential model of the relationship between filler orientation and applied voltage intensity and time; Based on the dielectric relaxation process, a first correlation model is established for the relationship between the dielectric constant of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature. A second correlation model is established for the relationship between the dielectric loss of a nonlinear conductive composite insulating material and the filler orientation, the frequency of the applied voltage, and the temperature. Based on the hopping conductivity behavior of electrons in nonlinear conductive composite insulating materials at high field strength, a third correlation model is established to explain the relationship between the conductivity of nonlinear conductive composite insulating materials, filler orientation, and temperature. The exponential model of filler orientation, applied voltage field intensity and time is substituted into the first correlation model, the second correlation model and the third correlation model and combined to obtain a spatiotemporal coupling model.

7. The dielectric parameter evaluation system for nonlinear conductive composite insulating materials according to claim 6, characterized in that: The exponential model of constructing the filler orientation degree and the field intensity and time of the applied voltage includes: The normalized amplitude of the current change during the filler orientation process is used as a quantitative indicator to characterize the filler orientation degree D. Based on the relaxation time constant τ required for complete particle orientation, the normalized current change curve is fitted using the following formula to obtain the relationship D with the applied voltage field intensity E and time t: D(E,t): Where a1 is the normalized current steady-state value, a2 is the normalized current initial value; By fitting the normalized curve of current change, the relationship between τ and E is obtained as follows: τ=a3 exp(-a4E) According to the relationship between D(E,t) and τ and E, an exponential model of D, E and t is constructed: Among them, a3 and a4 are fitting parameters.

8. The dielectric parameter evaluation system for nonlinear conductive composite insulating materials according to claim 6, characterized in that: It also includes a space-time coupling model building module for building space-time coupling models.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method for evaluating dielectric parameters of a nonlinear conductive composite insulating material according to any one of claims 1 to 5 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for evaluating dielectric parameters of a nonlinear conductive composite insulating material according to any one of claims 1 to 5 are implemented.

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