494 results about "Skin effect" patented technology

The invention relates to the technical field of fault diagnosis of power electronic equipment, and particularly discloses a fault analysis and diagnosis method and system for a mining high-voltage frequency converter, and the method comprises the steps: collecting the skin effect depth and parasitic parameter drift distance in real time under a high-frequency working condition through a multi-physics field sensor array; constructing three-dimensional current density distribution of the conductor based on a non-Euclidean space mesh generation technology, and dynamically correcting the equivalent resistivity of the conductor in combination with a metamaterial database to calculate a dynamic eddy current loss characteristic value; optimizing and solving the parasitic parameter time-varying evolution equation by using a quantum annealing algorithm to obtain a voltage peak sensitivity characteristic value; inputting the characteristic value into a pre-trained deep residual shrinkage network diagnosis model for multi-modal fusion analysis, and outputting a fault risk assessment result; according to the method, the problem of parasitic parameter time-varying characteristic modeling in the vibration environment is innovatively solved, and early warning of hidden faults is achieved.

The invention relates to a metal surface defect identification method and device based on artificial intelligence, equipment and a medium. The identification method comprises the following steps: synchronously acquiring an electromagnetic impedance signal and an optical image of a metal surface based on an eddy current sensor and an industrial camera; generating a spatially positioned interference area mask by quantifying cross-physics field interference intensity of the electromagnetic gradient and the optical edge feature; performing skin effect compensation on an electromagnetic signal by using the mask, and simultaneously performing shadow suppression on an optical image to realize physical field decoupling; a double-branch neural network is called to fuse the decoupled electromagnetic impedance features and optical texture features, and cross-modal associated joint feature expression is established; and analyzing the defect probability heat map based on the fused features, and outputting defect types and coordinates in combination with geometric feature matching. According to the method, the problem of defect feature mixing caused by mutual interference of electromagnetic-optical signals is solved, and the recognition precision and the positioning reliability of the micro defects are remarkably improved.

The invention provides a transformer magnetic core loss calculation method and system considering a variable loss coefficient, and the method comprises the steps: considering the influence of a high-frequency skin effect and a dynamic hysteresis loop on the iron core loss, and building a variable coefficient loss calculation formula; substituting the normalization constant into an integral form of an average value of the magnetic induction intensity in a period to obtain an equivalent frequency expression; and obtaining a generalized Steinmetz waveform coefficient formula under non-sine excitation based on the equivalent frequency expression and the variable coefficient loss calculation formula, and calculating the magnetic core loss of the nanocrystalline high-frequency transformer based on the formula.

The invention provides a current sensor. The current sensor adopts a magnetic-core-free design, and adopts a diversion row group with a special structure to guide a target current so as to enhance the electrifying capability of the current sensor and reduce the adverse effect of a high-frequency current skin effect on measurement. Based on the structural characteristics of the diversion row group, the magnetic sensitive component for measuring the target current and the corresponding sensing signal processing method are arranged in a matched manner, so that the measurement precision of high-frequency large current is improved, the suppression capability of an interference magnetic field is improved, and the signal-to-noise ratio of an effective measurement signal is increased. The current sensor provided by the invention is compact in structure, simple in manufacturing process, strong in electrifying capability and high in signal-to-noise ratio of a sensing signal, not only widens the measuring range of the current sensor, but also effectively improves the measurement precision of high-frequency large current, and expands the application range of the magnetic-core-free current sensor.

Low-loss lightweight high-power kilohertz alternating-current high-voltage electrical cables 1 usable in low pressure having a bundle 2 of metallic wires 3 being separated from each other by non-conductor layers 4 provided on the individual metallic wires, wherein the metallic wires 3 alternate between outer positions 5 and inner positions 6 in the bundle along a longitudinal extension 7 of the electrical cable in order to counteract skin effect in the electrical cable bundle 2, as well as enabling counteraction of proximity effect, when in use, an inner semi-conductive layer 8 of broad range temperature rated polymeric material surrounding said bundle 2 of metallic wires 3, and an insulating layer 9 of broad range temperature rated polymeric material surrounding and bonded to the inner semi-conductive layer 5, at least one of the metallic wires 3 being in electric contact with the inner semi-conductive layer 8 as well as a manufacturing method.

The invention relates to an electromagnetic shielding film and a circuit board, and the electromagnetic shielding film comprises a shielding layer, the thickness d of the shielding layer in a slicing state and in a preset observation range satisfies # imgabs0 #, the thickness uniformity of the shielding layer is less than or equal to 20% through the modes of adjusting a production technology and the like, the shielding layer with uniform thickness is formed, the consistency of impedance characteristics can be improved, and the electromagnetic shielding film has good electromagnetic shielding performance. And meanwhile, the skin effect of the shielding layer is reduced, the surface current is better borne, the influence of electromagnetic interference of a high-frequency and high-speed line on an internal circuit is reduced, the shielding effect of the electromagnetic shielding film on the high-frequency and high-speed line is improved, and the working reliability of the circuit board is further improved. Besides, the first protection layer forms an undulating surface through the particle member, and the shielding layer conformal to the undulating surface of the first protection layer can be grounded with the circuit board by using a downward projection, so that non-conductive particle grounding is realized, more use scenes are satisfied, and the material applicability is improved.

The invention discloses a CLLC resonance circuit circular litz wire winding loss calculation method and system, and the method comprises the steps: constructing a litz wire internal magnetic field intensity model, and determining a polar coordinate expression of the circular litz wire magnetic field intensity according to the litz wire internal magnetic field intensity model; determining a primary side current effective value and a secondary side current effective value of the CLLC resonance circuit; a proximity effect loss expression is determined, and according to the polar coordinate expression, the primary side current effective value, the secondary side current effective value and the proximity effect loss expression, a proximity effect loss value of the primary side and the secondary side of the CLLC resonance circuit is obtained through calculation; and determining a skin effect loss expression, and calculating the skin effect loss value of the primary side and the secondary side of the CLLC resonant circuit according to the polar coordinate expression, the primary side current effective value, the secondary side current effective value and the skin effect loss expression. The method improves the accuracy of loss calculation of the circular litz wire winding of the CLLC resonance circuit, and can be applied to the technical field of circuit measurement.

The invention discloses a skin sensitivity identification method and system based on a conditional generative adversarial network, and the method comprises the steps: constructing a pixel-to-pixel mapping relation data set according to a preset image mapping relation; inputting the collected real skin original image into a generative network structure Unet, and generating a false image with the same size as the skin original image; forming an image pair by the generated false image, the real skin original image and the real skin effect image, and inputting the image pair into a discriminator network PatchGAN to obtain a true and false image probability; calculating the loss Loss according to the output of the generator and the discriminator, and updating the network parameters of the generator and the discriminator by adopting a gradient descent method to obtain an image migration model; inputting a to-be-detected skin image into the image migration model to obtain a skin sensitive effect picture, and calculating a sensitive region area of the skin sensitive effect picture; and designing a skin sensitivity score mapping relation according to the area of the sensitive region, and evaluating the skin health state. The real-time performance is high, and the quality of the generated image is high.

The invention provides an optimized winding method and system for a high-frequency transformer winding. A comprehensive parameter database based on current density distribution data of a high-frequency switching power supply is established, the axial temperature of a winding layer is collected in real time in combination with a self-calibration multi-axis winding device, and tension and interlayer gap compensation parameters are generated through temperature gradient feedback. The tension parameter drives the machine to adjust the winding tightness, and the gap parameter optimizes the heat dissipation channel. And synchronously fusing the current distortion data of the LLC resonant topology and an electromagnetic field simulation result, and generating a resonant frequency adjustment signal to suppress abnormal high-frequency current distribution. And dynamic matching of winding tightness, current distribution and heat dissipation requirements is realized through cooperative control. According to the system, electromagnetic, mechanical and thermal field multi-dimensional linkage is adopted, the skin effect and hot spot concentration are reduced, the temperature rise gradient is balanced, and the high-frequency working condition stability is enhanced. According to the technical scheme, through electromagnetic, mechanical and thermal field cooperative regulation and control, the temperature rise peak value of the high-frequency winding is greatly reduced, and the efficiency is greatly improved.

The invention discloses an amorphous wire stress-electromagnetic coupling effect modeling method based on a micro-magnetism theory, and belongs to the technical field of magnetic materials and electromagnetic property regulation and control. According to the method, an amorphous wire micro-magnetic three-dimensional simulation model is constructed, solving is conducted through a finite element method, cross-scale simulation of magnetic domain structure evolution of the amorphous wire under the action of external stress is achieved, the change of effective magnetic conductivity of the amorphous wire under the action of different stress fields is further calculated, the skin effect and the magneto-impedance theory are fused, and the magnetic conductivity of the amorphous wire is calculated. And establishing an amorphous wire electromagnetic impedance spectrum model. According to the method, a quantitative mapping relation among the effective magnetic conductivity, the electromagnetic impedance characteristic and the external stress is established, a magnetic domain structure under the action of different stress fields can be deduced, and key parameters such as the effective magnetic conductivity and the electromagnetic impedance spectrum are output; theoretical guidance is provided for wide application of the amorphous wire in the fields of high-sensitivity stress sensing device design, broadband adjustable electromagnetic wave absorption / shielding, self-sensing composite material structure health monitoring and the like.

The invention relates to a copper foil and a preparation method and application thereof, the copper foil comprises an electrolytic copper foil layer and secondary long copper layers located on the surfaces of the two sides of the electrolytic copper foil layer, the maximum Feret diameter average value of crystal grains of the secondary long copper layers is 2.5-3 microns, and the maximum Feret diameter average value of crystal grains of the electrolytic copper foil layer is 1-2 microns. The maximum Feret diameter average value of grains of the secondary growing copper layer on the surface of the copper foil is 2.3-3 microns, the maximum Feret diameter average value of grains of the internal electrolytic copper foil layer is 1-2 microns, a structure with the grain size of the surface layer being large and the grain size of the inner layer being small is formed, and when the copper foil is used for transmitting a high-speed high-frequency electric signal, due to the skin effect of current, the high-speed high-frequency electric signal can be transmitted. More electric signals are transmitted along the surface layer of the copper foil, the grain size of the surface layer is large, the grain boundary is correspondingly reduced, and the obstruction to current is reduced, so that the loss of the electric signals is reduced, and the transmission integrity of the electric signals is improved.

The invention provides a gradient column crystal electromagnetic wire conductor and a preparation method thereof. According to the gradient column crystal electromagnetic wire conductor, the surface layer in the cross section direction of the conductor is of a coarse grain structure, the core part is of a fine grain structure, and the conductor is of a column crystal structure in the axial direction. The method comprises the following steps: firstly, adopting drawing and continuous annealing processes, and controlling drawing deformation, annealing temperature and heating time to enable recrystallization degrees of a surface layer and a core part to be different, so as to obtain a gradient crystal electromagnetic wire conductor; and then a directional heat treatment process is adopted, the drawing rate and the temperature gradient are controlled to enable the crystal to directionally migrate, and finally the gradient column crystal electromagnetic wire conductor is obtained. The gradient column crystal electromagnetic wire conductor is prepared for the first time, the special gradient column crystal structure can reduce electron scattering and relieve the skin effect, the conductivity of the copper conductor is improved to 103% IACS, the ductility is improved to 42%, and the preparation method can produce the high-power low-loss electromagnetic wire conductor and is applied to a process assembly line.

The invention relates to the technical field of electromechanical hydraulic systems, and particularly discloses a low-temperature cold start control method based on high-frequency injection, which comprises the following steps: analyzing a motor state, and carrying out observation and feed-forward compensation on disturbance caused by the motor state to a load torque and a viscosity coefficient through a sliding mode observer algorithm; according to the motor state, obtaining a state equation, constructing an extended sliding mode observer equation, deriving to obtain an observer error equation, and observing the load torque; analyzing the obtained load torque, wherein the motor load torque reflects the oil viscosity; high-frequency current injection, injection frequency control, skin effect enhancement and current amplitude control are carried out in a low-temperature state according to an oil viscosity result, copper loss and a high-frequency magnetic field eddy current effect are used for assisting heat generation, and according to a final oil viscosity result, when electromagnetic heat generation viscosity is reduced and a load is reduced, an injection voltage amplitude is gradually reduced. And after a normal starting condition is reached, switching to normal id = 0 control.

The invention discloses a coil structure-based length self-sensing method for high polymer twisted artificial muscle, which comprises the following steps of: firstly, enabling the artificial muscle to be equivalent to N equidistant circular current loops, establishing an inductance calculation formula by combining a Biot-Savart law and a magnetic field superposition principle, and breaking through the limitation of a traditional solenoid model on a helical angle; then through MATLAB numerical simulation and iterative computation, fitting to obtain a power function describing the relation between inductance and length; and finally, proposing a parameter dynamic correction mode based on single-time initial inductance measurement according to complex factors such as actual magnetic flux leakage and skin effect, and realizing rapid adaptive calibration by adjusting a parameter b. In a word, the method creatively combines theoretical modeling with experimental correction, the sensing precision in a dynamic stretching scene is remarkably improved while the inductance-length macroscopic trend prediction capability is ensured, dependence on a large amount of experimental data is not needed, and the method has good engineering applicability and is worthy of popularization.

The invention relates to the technical field of metal composite wires, in particular to a manufacturing method and device of a double-layer metal composite wire. The manufacturing method comprises the following steps that S1, a double-layer metal composite blank rod is taken, the double-layer metal composite blank rod comprises a core layer metal wire and a metal coating layer coating the outer side of the core layer metal wire, and the tensile strength of the metal coating layer is larger than that of the core layer metal wire; s2, the double-layer metal composite blank rod is subjected to multi-pass drawing, a composite metal wire is obtained, pulse current is applied to a metal coating layer located in a drawing area in the drawing process, the mechanical property of the metal coating layer is made to be matched with that of a core layer metal wire, and interface fracture is restrained; and S3, the composite metal wire is subjected to annealing treatment, and the composite metal wire is obtained. According to the method, the effect that only the metal coating layer is softened is achieved by controlling pulse current parameters and utilizing the skin effect and the electroplastic performance, the drawing deformation of the inner metal and the drawing deformation of the outer metal are consistent, the quality of the composite wire is improved, and the method is suitable for the situation that the conductivity of the inner-layer metal is larger than that of the outer-layer metal.

The invention relates to the technical field of transformers, and discloses a transformer broadband modeling method and system, electronic equipment and a medium, and the method comprises the steps: segmenting a primary winding and a secondary winding of a converter transformer, and dividing the primary winding and the secondary winding into a plurality of segmented coil units; coupling the plurality of segmented coil units to obtain an initial segmentation model of the converter transformer; carrying out equivalence on element parameters of the initial segmentation model of the converter transformer based on a high-frequency skin effect; and inputting the equivalent element parameters into the initial segmentation model of the converter transformer to obtain a segmentation model of the converter transformer. According to the method, the high-frequency characteristics of the converter transformer can be simulated more accurately, and the high-frequency impedance characteristics of the transformer can be analyzed accurately, so that the simulation effect of the converter transformer is more accurate.

The invention discloses an application for reducing a conductor skin effect based on an electron deep protective agent, and relates to the technical field of current distribution regulation. Through real-time monitoring and self-adaptive regulation, current density is transited to a deep position layer by layer, a surface layer concentration phenomenon is remarkably reduced, dynamic response can be realized in a frequency change environment, and the current density is reduced. Meanwhile, an electron deep protection layer is introduced, current distribution can be stabilized and direct impact of frequency fluctuation can be relieved in a high-frequency environment, the anti-loss capability of the surface layer of the conductor is improved, the overall stability of the conductor is enhanced, the service life of equipment is prolonged, in addition, a closed-loop feedback control mechanism is adopted, and the service life of the equipment is prolonged. The adaptive filter monitors the current concentration condition in real time and automatically adjusts the current distribution, so that the current density always tends to a uniform and smooth transition state, the smoothness and stability of the current distribution are improved, and transient loss caused by current concentration under frequency fluctuation can be reduced.

The invention relates to the technical field of radio frequency integrated circuits and advanced semiconductor packaging, in particular to a radio frequency resistor calibration structure based on an RDL process and a manufacturing method, and the radio frequency resistor calibration structure comprises a main resistor module, a redundant resistor module, a laser fine tuning module, a shielding layer module and a temperature compensation module. The main resistor module is sputtered into a film through a low-temperature coefficient metal alloy, and the high-frequency skin effect is reduced by adopting a snakelike or interdigital geometric layout; and the redundant resistor module drives metal ions to migrate through a narrow-neck structure and an electromigration effect, and compensates photoetching line width deviation and uneven sputtering thickness. The laser fine tuning module adjusts a conductive path through selective ablation or annealing of pulse laser, and forms closed-loop calibration in combination with real-time feedback of the metal induction electrode. And the consistency regulation and control of radio frequency circuit parameters of a packaging level are realized.

A composite wire bundle for a stator winding, a stator including a composite wire bundle, and a method of forming a composite wire bundle. The composite wire bundle includes a plurality of copper wires, wherein each of the plurality of copper wires include a first surface. The composite wire bundle also includes a copper-graphene multilayer composite applied to the first surface of each of the plurality of copper wires, wherein the copper-graphene multilayer composite includes a second surface. Further, the composite wire bundle includes a fluoropolymer matrix formed around the second surfaces and a jacket encapsulating the fluoropolymer matrix.

The invention relates to the technical field of submarine cables, in particular to a high-performance wet-type dynamic submarine cable which comprises a conductor, and a filling strip, a cabling wrapping tape, an inner sheath, an armor and an outer sheath are sequentially arranged on the outer side of the conductor from inside to outside. According to the high-performance wet-type dynamic submarine cable, the compressed circular copper oxide water-blocking conductor is adopted, the insulating layer is arranged on the surface of the copper conductor, the skin effect of the conductor is reduced, and the current-carrying capacity can be improved; the armoring is a double-layer reverse armoring, an inner layer bonding and outer layer non-bonding structure is adopted, through reverse twisting, torsion generated in the twisting process of the cable is effectively counteracted, so that the knotting and fracture risks caused by torsion in the laying and using processes of the cable are remarkably reduced, the anti-pressure capability and the dynamic flexibility are balanced through the layered design, and the service life of the cable is prolonged. The sliding frequency and the abrasion risk of outer-layer steel wires are reduced.

The invention relates to the technical field of semiconductors, in particular to a precise circuit board with an ultrahigh-frequency multilayer memory bank, which comprises a functional circuit surface layer, a high-speed signal layer, an upper grounding layer, an upper waveguide insulating layer, a power supply layer, a lower waveguide insulating layer, a lower grounding layer and a functional circuit bottom layer, the functional circuit surface layer, the high-speed signal layer, the upper grounding layer, the upper waveguide insulating layer, the power supply layer, the lower waveguide insulating layer, the lower grounding layer and the functional circuit bottom layer are sequentially stacked from top to bottom, a conductive groove is formed in the high-speed signal layer in a penetrating mode, a conductive column is arranged in the conductive groove in a matched mode, and waveguide grooves are formed in the tops of the upper waveguide insulating layer and the lower waveguide insulating layer. And a waveguide tube is arranged in the waveguide groove. According to the scheme provided by the invention, by arranging the trapezoidal conductive columns and utilizing the function of dispersing high-frequency current distribution by the asymmetric cross sections of the conductive columns, the skin effect is reduced, the signal integrity is improved, and the effect of optimizing the high-speed signal transmission time sequence consistency is achieved through the obliquely arranged waveguide tubes.

The invention discloses a solid-state transformer magnetic core loss calculation method adaptive to electric power system characteristics. The method comprises the following steps: firstly, collecting actually measured ferrite core loss data, and fitting hysteresis and eddy current loss parameters of a classical two-item model; setting 100kHz as a low-frequency and medium-high-frequency demarcation point through an eddy current and magnetic hysteresis loss balance point and a relaxation effect, and dividing three frequency bands by taking a skin effect characterization parameter greater than 2 as a medium-frequency and high-frequency demarcation point; adding a specific compensation item according to the loss characteristics of each frequency band, and constructing a segmented two-item model with compensation items; and fitting the parameters by adopting an L-M algorithm to calculate the total loss. According to the method, through frequency and flux density interval double division and compensation item introduction, the influence of nonlinear factors is effectively considered, and the magnetic core loss calculation precision is remarkably improved.

The utility model relates to a current detection device used for a copper bar, the current detection device is installed on the copper bar, one side or two sides of the copper bar are provided with gaps, the current detection device comprises a current detection chip and a shielding case, the shielding case covers the copper bar, and the current detection chip is parallel to the copper bar and is installed on the surface of the copper bar or above the surface of the copper bar. Compared with the prior art, one side or two sides of the copper bar are provided with the gaps, so that an internal magnetic field of the shielding cover translates in the horizontal direction when the alternating current changes, and the influence of the skin effect on the induction magnetic field intensity of the current detection chip is reduced; the current in the copper bar can be detected without an additional communication wire harness or a shell, so that the size is greatly reduced, and the cost is reduced; current detection can be carried out by arranging the current detection chip on the surface of the copper bar, the installation position can be flexibly adjusted according to the internal space requirement of the product, and the application range is wide.

The invention provides an oriented silicon steel magnetic field intensity prediction method and system considering a skin effect under direct current magnetic bias high-frequency excitation, and belongs to the technical field of soft magnetic material high-frequency hysteresis performance analysis. The method comprises the following steps: determining magnetic field intensity corresponding to static hysteresis loss of oriented silicon steel under direct current magnetic bias excitation; determining the magnetic field intensity corresponding to the eddy current loss of the oriented silicon steel; determining the magnetic field intensity corresponding to the abnormal loss of the oriented silicon steel; and according to the magnetic field intensity corresponding to the static magnetic hysteresis loss, the eddy current loss and the abnormal loss, constructing a dynamic magnetic hysteresis model of the oriented silicon steel under direct current magnetic bias high-frequency excitation so as to predict the magnetic field intensity of the oriented silicon steel. In the process of determining the magnetic field intensity corresponding to the eddy current loss of the oriented silicon steel, the direct-current component of magnetic flux density excitation and the non-uniform characteristic of magnetic field distribution under high-frequency excitation are considered, and accurate characterization of hysteresis and loss under direct-current magnetic bias high-frequency excitation is achieved.

The invention discloses a low-alternating-current-loss motor stator and a stator winding conductor design method thereof. The method comprises the following steps of S1, determining structural parameters of a stator winding conductor; and S2, on the basis of a preset rapid estimation model of alternating current loss, temperature rise and motor output power based on the structural parameters, searching an optimal solution of a structural parameter combination by taking the minimum overall alternating current loss of the stator winding conductor as a target in a value range of the structural parameters of the stator winding conductor so as to obtain an optimal structural parameter combination of the stator winding conductor. When the optimal structural parameters of the stator winding are applied to the motor, the skin effect and the neighbor effect of the conductor of the stator winding under the high-frequency working condition can be effectively inhibited, so that the alternating-current loss and the temperature rise of the conductor of the stator winding are reduced.

The invention discloses a vertical PCB winding structure capable of reducing alternating current loss and application thereof, and belongs to the field of power electronics. The vertical PCB winding structure comprises a PCB substrate, the PCB substrate is provided with a magnetic core in a slotting mode, the magnetic core is provided with a cavity, a plurality of narrow grooves are formed in the portion, in the cavity of the magnetic core, of the PCB substrate, vertical windings are arranged on the two side walls of the narrow grooves, and the vertical windings are connected through plane windings. By changing the arrangement mode of the conductors, the current density distribution condition in the conductors at high frequency is improved, so that the influence of a skin effect and a proximity effect on device impedance is reduced, and the low-loss and high-efficiency PCB winding is realized.

The invention discloses a super-magnetostrictive transducer electromagnetic energy loss optimization method based on SCReg-PGNN, and the method comprises the steps: building a super-magnetostrictive bar magnetic energy loss test platform to test the magnetic energy loss under different working conditions, then carrying out the precise calculation of the electromagnetic loss of an excitation coil through considering the skin effect, proximity effect and fringe effect, and carrying out the optimization of the electromagnetic energy loss of the excitation coil. And finally, establishing an electromagnetic energy loss model of the high-power giant magnetostrictive transducer based on SCReg-PGNN, carrying out rapid calculation on electromagnetic loss characteristics of the giant magnetostrictive transducer, and finally, searching for optimal electromagnetic structure parameters of the high-power giant magnetostrictive transducer by means of a particle swarm optimization algorithm of non-dominated sorting. According to the method, high-precision modeling and response prediction of the electromagnetic loss of the transducer can be realized under the conditions of multiple working conditions and multivariable input, and collaborative optimization of structural parameters under multiple targets is further realized, so that the overall energy efficiency and the working reliability of a transducer system are improved.

The invention discloses a multi-process parameter identification method for an induction motor. According to the method, different parameter identification strategies are provided for different common working conditions in combination with an induction motor transient mathematical model. For motor starting and steady-state operation conditions, current deviation and impedance deviation are respectively adopted as objective functions, and motor parameters are identified by using an improved particle swarm algorithm. On the basis, accurate parameters such as stator and rotor resistance, stator and rotor leakage inductance and the like are provided for a control strategy during long-term operation of the motor by introducing a parameter change coefficient and considering nonlinear characteristics such as skin effect, magnetic circuit saturation, temperature and the like. According to the method, historical operation data of the motor are fully utilized, invasive experiments such as locked-rotor and signal injection do not need to be additionally carried out, and the method has the advantages of being good in engineering practicability and accurate in identification result.

The invention discloses a metamaterial RFID (Radio Frequency Identification) anti-interference antenna structure for a severe environment and a manufacturing method of the metamaterial RFID anti-interference antenna structure. The middle layer of a substrate of the antenna structure is made of corrosion-resistant polyether-ether-ketone resin doped carbon nanotubes; the upper-layer metal patch of the electromagnetic band gap unit array and the lower-layer metal layer of the annular gap are respectively attached to the upper surface and the lower surface of the middle layer of the substrate; and a self-adaptive impedance matching module is arranged at the joint of the equipment antenna and the feeder line. And each unit in the electromagnetic band gap unit array vertically penetrates through the substrate through a metalized via hole and is connected with the upper-layer metal patch and the lower-layer metal grounding layer of the substrate to form an LC resonance unit. The skin effect of eddy current on the metal surface can be counteracted through the reverse induction current, the loss of energy on the metal surface is greatly reduced, and the radiation efficiency of the metal surface is remarkably improved. In a complex electromagnetic environment, signals can be radiated and received more efficiently, the communication stability and reliability of an RFID system are effectively enhanced, and the probability of signal loss and error codes is reduced.

The invention belongs to the technical field of non-magnetic material nondestructive testing, and discloses a non-ferromagnetic material thickness and conductivity synchronous measurement method based on eddy current phase characteristics, and the method comprises the specific steps: S1, estimating the conductivity and thickness range of a to-be-tested piece based on data such as a product specification or an industrial standard; s2, determining excitation frequency according to a frequency selection criterion (high frequency enables the skin effect depth to be smaller than 1 / 3 of the thickness, and low frequency enables the skin effect depth to be larger than two times of the thickness of the sample); s3, an eddy current method is adopted to obtain the impedance variable quantity phase of the to-be-measured non-ferromagnetic material; and S4, substituting the phases into corresponding simplified model formulas respectively, and obtaining the conductivity and the thickness at the same time. Aiming at the problems of multiple calibration, blindness in excitation frequency selection, low single-parameter measurement efficiency and the like in conductivity or thickness measurement by an existing eddy current method, double-parameter output of single measurement is realized, multiple calibration and inversion calculation are not needed, the calculation is simple, rapid and accurate, the hardware cost is low, and the applicability is wide.