82 results about "Impedance properties" patented technology

The invention relates to a multi-frequency bioelectrical impedance-based body fat accurate measurement method and system. The method comprises the following steps: receiving a mode selection instruction sent by a user to determine a current working mode; if the mode is a rapid measurement mode, applying single reference frequency and reference current intensity excitation, obtaining a single group of bioelectrical impedance data, and calculating a rapid body fat rate result; if the measurement mode is an accurate measurement mode, acquiring bioelectrical impedance data under a plurality of preset frequencies and a plurality of preset current intensities through a complete electrode system, performing signal processing on the data, extracting impedance amplitude and phase information, constructing an impedance characteristic curve, extracting characteristic parameters related to the body fat rate from the impedance characteristic curve, and calculating the body fat rate based on the characteristic parameters. And obtaining a final body fat rate result of the accurate measurement mode. According to the method, the body fat rate can be accurately measured, and the accuracy and reliability of a measurement result are improved.

The invention discloses an energy storage power station oscillation risk monitoring method and device based on impedance network aggregation, and belongs to the field of power systems, and the method comprises the steps: obtaining impedance information and a first network topology structure of each device in an energy storage power station; obtaining a first impedance network framework by adopting a hierarchical calculation method; based on the framework and the impedance information, an impedance network aggregation method is adopted to calculate impedance characteristics of all frequency points to form full-frequency-domain impedance characteristics, and the oscillation risk of the energy storage power station is monitored according to the full-frequency-domain impedance characteristics and actual impedance data. The problem that it is difficult to accurately monitor the oscillation risk of the energy storage power station while guaranteeing the calculation efficiency in the prior art can be solved.

The invention relates to the field of chip detection, and discloses a high-efficiency chip detection system and method, which are used for realizing long-term performance degradation detection of a chip. Comprising the following steps: synchronously acquiring power pin electric signals and chip surface thermal imaging data to generate an electrothermal coupling characteristic data set in a working state of a to-be-tested chip, and extracting impedance and heat conduction characteristic parameters through impedance spectroscopy analysis and thermal time constant calculation. And analyzing an internal signal transmission path based on impedance characteristic parameters to obtain path characteristic parameters, establishing a mathematical model of dynamic current and working voltage of the chip by combining the two, generating a system identification result, and finally generating a chip detection result and fault positioning information by integrating various parameters. According to the invention, system benchmark testing and environmental interference monitoring and compensation are carried out, and high precision and high robustness of a detection result are realized.

The invention discloses a cable high-frequency impedance characteristic analysis method based on bipolar trapezoidal wave excitation, and belongs to the technical field of power equipment state monitoring and fault diagnosis. In order to solve the problems of low test efficiency, insufficient high-frequency parameter modeling precision and weak anti-interference capability in cable high-frequency impedance characteristic analysis of a traditional sine wave excitation method, the method comprises the following steps: generating an odd-symmetry bipolar trapezoidal wave excitation signal with specific frequency and amplitude, and injecting the signal into the head end of a cable to be tested through a coupling device after power amplification; synchronously acquiring a high-frequency response signal of the key position of the cable under the excitation of the bipolar trapezoidal wave by using a data acquisition system; preprocessing the high-frequency response signal, converting the high-frequency response signal into a frequency domain through Fourier transform, calculating input impedance of the cable under different harmonic frequencies, and synthesizing a broadband impedance spectrum; based on the broadband impedance spectrum, the amplitude-frequency characteristic and the phase-frequency characteristic of impedance are analyzed, and cable state evaluation, partial discharge detection, insulation defect diagnosis or fault point positioning are realized. The method is used for an electric power system.

The invention relates to an electrical equipment insulation aging evaluation and early warning method and system capable of predicting maintenance, and belongs to the technical field of electrical engineering and automation. The method comprises the following steps: acquiring insulation state data of electrical equipment, establishing a performance-aging curve, analyzing local aging characteristics through an insulation tolerance test to obtain insulation deterioration degree data, constructing an insulation deterioration prediction framework, and generating an operation record containing insulation steady state evaluation and a discharge form, insulation maintenance information is configured in combination with a maintenance efficiency index to form an insulation deterioration evaluation scheme, spectrum analysis, impedance characteristic analysis and hot area layout identification are performed on an insulation state, an insulation material attenuation period is verified by using a dielectric frequency domain response technology, and equipment aging early warning information is obtained. And when the prediction track meets the maintenance efficiency index, the insulation attenuation parameter is updated, and the self-adaptive iteration of the insulation degradation prediction framework is realized, so that the prediction precision and the maintenance timeliness of the insulation aging of the electrical equipment are improved.

The invention provides a passive and active self-adaptive impedance reconstruction control method of a doubly-fed converter, which adopts a staged mixed damping strategy: before a stator is connected to a grid, a passivity-based parallel LC resonance suppressor is adopted to provide inherent broadband passive damping for a system. After a stator is connected to a grid, grid-side self-adaptive trapped wave active damping control based on online impedance identification is switched, and specific harmonic peaks caused by interaction of background harmonic waves and impedance of a power grid are accurately suppressed by sensing impedance characteristics of the power grid in real time and dynamically adjusting parameters of a wave trap. The passive active self-adaptive impedance reconstruction control method for the doubly-fed converter has the beneficial effects that the passive active self-adaptive impedance reconstruction control method for the doubly-fed converter has the function of comprehensively inhibiting the resonance risk caused by interaction between a doubly-fed wind turbine generator and a power grid in a broadband range. The technical problem that in the prior art, a damping frame which is in adaptive cooperation with the operation state of the double-fed system cannot be constructed is solved.

The invention discloses a dynamic test method and system for tissue frequency domain impedance characteristics, and belongs to the technical field of medical detection. The system comprises an energy generator, a bipolar scalpel, a signal generator, a radio frequency power amplifier module, a control unit, two loop switches, a sampling probe and a test unit. An electrode of the bipolar scalpel is used for being in contact with a biological tissue to be subjected to frequency domain impedance characteristic testing; the energy generator is connected with the first loop switch and is used for outputting an electric resection / electrocoagulation signal to the biological tissue so as to dynamically reproduce the state change of the biological tissue; and the signal generator inputs a broadband excitation voltage signal to the biological tissue through the radio frequency power amplifier module and the second loop switch. The control unit is used for coordinating on-off of the two loop switches. The sampling probe is used for collecting voltage and current signals of the double electrodes in real time and feeding back the signals to the testing unit. The test unit generates a real-time impedance characteristic spectrogram of the biological tissue along with frequency change. The tissue impedance change can be monitored on line in real time.

The invention discloses a tissue broadband domain impedance characteristic test system and method, and belongs to the technical field of medical detection. The system comprises a signal acquisition and control unit, a radio frequency power amplifier module, a protective resistor, a bipolar scalpel, two voltage probes and a sampling resistor module, an electrode of the bipolar scalpel is in contact with a biological tissue to be subjected to impedance characteristic test; the signal acquisition and control unit outputs a broadband excitation voltage signal, the broadband excitation voltage signal is amplified by the radio frequency power amplifier module, and the amplified signal sequentially passes through the protective resistor, the sampling resistor module and the electrode to be input into biological tissue; the two voltage probes are respectively used for sampling voltage signals of the electrode and the sampling resistor module in real time and feeding back the voltage signals to the signal acquisition and control unit; and the signal acquisition and control unit obtains impedance amplitudes and impedance phases of the biological tissue under various frequencies through Fourier transform, and impedance characteristic testing is completed. Data support can be provided for the design of the energy surgical instrument.

The invention discloses a new energy grid-connected inverter parameter identification method fusing time-frequency domain dynamic characteristics, and the identification process is divided into three stages: a time domain identification stage, a frequency domain identification stage and a time-frequency domain characteristic verification stage. According to the method, a new energy grid-connected inverter impedance characteristic curve database is established by combining time domain and frequency domain operation characteristic curves of a new energy grid-connected inverter'white box model 'of a known control strategy, and the operation characteristic curve in the impedance characteristic curve database is compared with the operation characteristic curve of a new energy grid-connected inverter'black box model'. And the control mode conforming to the operation characteristics of the new energy grid-connected inverter is identified and obtained. Compared with an existing new energy inverter parameter identification method, the new energy inverter parameter identification method has the advantages that the modeling process of the new energy inverter is simplified, and the new energy inverter parameter identification efficiency is greatly improved; and the input of a new control strategy is supported, and a guarantee is provided for the identification range and precision of the impedance characteristic curve database.

The invention discloses a multi-frequency electromagnetic detection signal generation method for composite material defect detection, and relates to the technical field of electromagnetic detection, and the method comprises the following steps: based on composite material structure layering, collecting response voltages of a composite material defect-free standard sample under different excitation frequencies, different structure layers and different directions; carrying out normalization processing on the response voltage, and calculating through an Ohm law to obtain an impedance characteristic curve of the composite material; finding an optimal frequency excitation point from the impedance characteristic curve, and calculating an impedance matching coefficient according to the optimal frequency excitation point; and probe calibration is carried out based on the impedance matching coefficient, and multi-frequency composite information is generated and output to an excitation coil of the excitation probe. Impedance matching of the composite material, the excitation coil and the differential coil is realized.

The embodiment of the invention provides a cable early-stage fault positioning method and device based on metal sheath parameters. The cable early-stage fault positioning method based on the metal sheath parameters comprises the steps that a cable electrical model is established based on electrical parameters; obtaining a key electrical quantity, comparing the key electrical quantity with a preset threshold value, and determining a comparison result; determining fault feature information based on the comparison result; and determining a fault point based on the fault feature information and the fault positioning equation. According to the scheme, the impedance characteristic of the cable metal sheath is utilized, and the parameters of the metal sheath are introduced into a fault positioning algorithm. According to the method, the positioning error is effectively reduced, the accuracy of the early fault positioning process is remarkably improved, and a more efficient and more accurate solution is provided for solving the detection and positioning problems of the power system in the early stage of the fault.

The invention relates to the technical field of microwaves, in particular to a broadband antenna matching system based on a 4: 1 impedance conversion balun, which comprises the 4: 1 impedance conversion balun, an adjustable impedance matching network, a radio frequency monitoring unit and a logic control unit, the logic control unit is configured to receive forward power and reflection power signals and calculate to obtain a standing-wave ratio or a reflection coefficient under a current working frequency point; comparing the standing-wave ratio or the reflection coefficient with a preset threshold value; based on a comparison result, executing an adaptive matching algorithm, and iteratively generating and outputting a new digital control signal to drive a variable reactance element in the adjustable impedance matching network to change the value of the variable reactance element; and through closed-loop feedback control, the impedance of the adjustable impedance matching network is dynamically optimized. By modifying an algorithm parameter or a lookup table in the logic control unit, the same hardware platform can easily adapt to antennas with different impedance characteristics and different frequency bands. And the design flexibility and the product universality are greatly enhanced.

The invention provides a wide-temperature high-frequency high-impedance manganese zinc ferrite material and a preparation method thereof, and relates to the technical field of magnetic materials. The manganese zinc ferrite material comprises main components and auxiliary components, the main components comprise Fe2O3, ZnO, Mn3O4 and MgO, and the auxiliary components comprise Na2O, Co2O3, Li2O and K2O; the high-frequency high-impedance manganese-zinc ferrite material with the wide-temperature characteristic provided by the invention has the characteristics of high magnetic conductivity and high resistivity, is good in high-frequency impedance characteristic, relatively stable in magnetic conductivity and high-frequency impedance at the temperature of-40 to 120 DEG C, small in temperature influence change, and capable of stably working in an environment with sudden temperature change; and stable and safe operation of instruments and equipment is ensured.

The invention relates to the technical field of new energy power systems, in particular to a modeling method and device for a nonlinear frequency domain coupling impedance model of a new energy grid-connected system. The method comprises the steps of establishing an impedance model of the single-machine converter, analyzing a frequency sweeping result of the single-machine converter obtained in the impedance model establishing process according to the multi-time scale characteristic of a controller, obtaining an impedance characteristic analysis result of each frequency band, analyzing corresponding parameters of the impedance model under different frequency bands according to the impedance characteristic analysis result of each frequency band, and calculating the impedance model of the single-machine converter according to the parameters. According to the obtained impedance transfer function and parameters of each frequency band, establishing an output impedance mathematical model of the inverter under all working conditions; according to the output impedance mathematical model, the feeder equivalent impedance of the feeder from the tail end to the head end is determined, and the overall output impedance of the multiple parallel feeder lines at the collection cabinet is calculated. According to the method, the problems that a multi-dimensional coupling mechanism is not clear and the equivalent modeling precision needs to be improved in the process of expanding the single machine characteristics to the whole station level in the prior art can be solved.

The invention provides an EPS system short-time overcurrent protection method, device and equipment and a storage medium, and belongs to the technical field of EPS system control, and the method comprises the steps: S1, when a real-time current is greater than a preset current threshold value, executing steps S2-S5; s2, calculating a current change rate; s3, generating a Vds voltage reasoning threshold value; s4, working condition parameters are obtained, working condition correction factors are determined, and the Vds voltage reasoning threshold value is corrected; s5, the Vds voltage is compared with the Vds voltage reasoning threshold value; and S6, repeatedly executing the steps S2-S5, and cutting off the driving circuit when the fault frequency is greater than a first preset frequency threshold. According to the short-time overcurrent protection method, device and equipment for the EPS system and the storage medium provided by the invention, the influence of impedance characteristic change and parasitic inductance of a power loop on a judgment result can be effectively prevented, so that the false alarm probability is reduced.

The invention discloses a biological high-frequency electrical impedance characteristic real-time acquisition method and system, and the method comprises the steps: transmitting a high-frequency excitation signal to a first electrode pair through a coaxial shielding line, and obtaining a voltage signal U0 of a sampling resistor R0 connected in series with a signal transmission loop of the first electrode pair; a signal transmission loop of the electrode pair I is connected with a contact resistor RL in series to form an RC filter circuit together with the coaxial shielding line, and passive RC compensation is arranged between the electrode pair I and the living body; the voltage UZ on the impedance of the living body is obtained by the coaxial shielding line through the electrode pair II, and passive RC compensation is arranged between the electrode pair II and the living body; according to the sampling resistance R0, the voltage U0 and the voltage UZ, the bioelectrical impedance value RZ of the to-be-measured organism is calculated.

The method for modeling impedance of DAB converter based on multi-LC resonant unit and predicting high-frequency oscillation frequency comprises the following steps: step 1, measuring impedance characteristics of a high-frequency transformer and an external inductor according to a determined DAB converter topology; step 2, calculating parasitic parameters of the high-frequency transformer and the external inductor according to the measurement results of the impedance characteristics; and step 3, judging the number of high-frequency oscillation frequencies for different configurations and parameter sizes of the external inductor and the leakage inductance of the high-frequency transformer, and selecting a high-frequency oscillation frequency prediction formula to obtain a result. The frequency variation effects of the external inductor and the leakage inductance of the high-frequency transformer are comprehensively considered, the parasitic parameters are effectively extracted through accurate modeling, and the oscillation prediction formula is derived based on the transfer function, so that the deep physical mechanism of the high-frequency oscillation is revealed, and systematic and guiding theoretical basis and engineering practice support are provided for the high-frequency oscillation suppression scheme under different structural topologies and parameter combinations.

The invention discloses an MMC impedance prediction method and system of a flexible interconnection system, equipment, a medium and a product, and the method comprises the steps: injecting positive and negative sequence voltage disturbances with different voltage frequencies into a pre-constructed MMC simulation model of a network construction type flexible interconnection system under a plurality of different working condition variables; the method comprises the steps of obtaining output voltage and current time-domain signals of an MMC under disturbance of multiple different voltage frequencies, obtaining output voltage and current frequency-domain data through fast Fourier analysis, determining equivalent impedance of the MMC of the network-forming flexible interconnection system at each frequency according to the output voltage and current frequency-domain data, and determining the equivalent impedance of the MMC of the network-forming flexible interconnection system according to the equivalent impedance. And taking the equivalent impedance and the working condition variable corresponding to each frequency as mapping samples, constructing a training data set, and training the initial fuzzy neural network, thereby enabling the trained MMC equivalent impedance prediction model to output an equivalent impedance prediction value of the MMC at the current calculation moment. Therefore, the impedance characteristics of the network-forming type MMC can be accurately represented in a wide working range.

The invention is suitable for the technical field of impedance calculation, and provides a new energy station impedance calculation method, which comprises the following steps: inputting acquired broadband impedance characteristic data into a preset clustering algorithm model for clustering analysis, and generating a plurality of unit clusters; calculating an equivalent impedance characteristic of the current cluster, and determining an equivalent frequency domain network equivalent FDNE unit corresponding to the current cluster according to the equivalent impedance characteristic; constructing a function taking maximization of a stability margin and minimization of a harmonic distortion rate as optimization targets, and solving an optimal solution set of the function by taking key parameters of each equivalent FDNE unit of the equivalent frequency domain network as optimization variables; according to the actual electrical topology of the new energy station, the optimized FDNE units are connected, and a full-field equivalent simulation model is constructed; calculating the equivalent impedance characteristic of the grid-connected point of the new energy station through a full-field equivalent simulation model; the calculation efficiency is greatly improved on the premise of ensuring the modeling precision.

A power line grounding line detection method and apparatus. The method comprises: measuring a first impedance of a power line at a first measurement frequency, and measuring a second impedance of the power line at a second measurement frequency (S101); on the basis of the first measurement frequency and the first impedance corresponding thereto, and the second measurement frequency, and on the basis of the second impedance corresponding thereto, determining an impedance property of the power line (S102); calculating a third impedance of the power line on the basis of the impedance property of the power line, and calculating a reactance factor on the basis of the third impedance (S103); obtaining a grounding line installation state of the power line on the basis of the reactance factor, the third impedance, and the impedance property (S104). The present method resolves the technical problems in the prior art of low detection accuracy and insufficient validity, which make relatively large errors likely, causing detection faults.

The invention discloses a method for automatically measuring impedance of a power electronic converter based on a real-time simulation platform, which comprises the following steps of: adding a disturbance injection module and a data acquisition module into a simulation model, and calculating load flow or performing time domain simulation to obtain a steady-state working point; parameters needing to be measured are determined in the disturbance injection module; according to the measurement starting time, the wave recording starting time, the real-time simulation step length, the sampling factor, the storage file size and the storage file of a data acquisition module in the real-time simulation platform are determined, and according to the measurement starting time, the frequency disturbance duration of each time, the disturbance interval waiting time and the total frequency number of the frequency sequence, the real-time simulation total duration is determined; injecting disturbance, and acquiring a voltage and current data set of the tested port; and calculating the impedance value of the total frequency number of the frequency sequence, and generating a full-band impedance characteristic curve. According to the measurement method disclosed by the invention, the impedance scanning efficiency is improved, and the impedance of the new energy equipment is quickly and accurately acquired.

The invention discloses a grid-connected oscillation judgment method, system and equipment of a power electronic converter and a medium, and particularly relates to the technical field of oscillation judgment, and the technical key points are as follows: constructing an amplitude-frequency curve and a phase-frequency curve by using the SISO impedance of a power grid and the SISO impedance of the power electronic converter obtained by broadband impedance measurement; in the amplitude-frequency curve, obtaining a frequency value when the SISO impedance characteristic amplitude of the power grid is equal to the SISO impedance characteristic amplitude of the power electronic converter, and obtaining a phase difference of the same frequency value in the phase-frequency curve; and combining the phase difference with a pre-constructed broadband oscillation criterion to obtain an oscillation judgment result of the converter grid-connected system. The SISO impedance characteristic of the power grid and the SISO impedance characteristic of the power electronic converter, which are obtained by broadband impedance measurement, are utilized to more conveniently and quickly judge whether the system has the risk of broadband oscillation caused by harmonic amplification of the system; meanwhile, a broadband oscillation criterion is provided, and a critical oscillation region is introduced, so that the grid-connected oscillation criterion is defined more clearly.

A method for determining the state of at least one sensor whose mechanical behaviour is nonlinear as a function of the amplitude of the pressure exerted against the sensor, the sensor and an electromechanical transducer being able to be coupled to a support, the method comprising the steps of: applying an electrical signal at a first amplitude to the terminals of the first electromechanical transducer, and determining a first set of values of a parameter characteristic of the electrical impedance of the first electromechanical transducer in response to the application of the electrical signal; applying the electrical signal at a second amplitude to the terminals of the first electromechanical transducer, and determining a second set of values of the parameter characteristic of the impedance; measuring a deviation between the first set of values and the second set of values; determining a state of the sensor as a function of the deviation between the first set of values and the second set of values.

The invention discloses a robot VPX case shielding effectiveness calculation method based on a TLM theory, and the method comprises the steps: dividing a transmission line into a plurality of line segments, and enabling the line segments to be equivalent to a circuit model; the equivalent circuit is analyzed, an equivalent circuit equation is obtained through the Kirchhoff's law, and current and voltage distribution is obtained; calculating impedance characteristics and transmission constants of the equivalent transmission lines; establishing an equivalent transmission line model of the single aperture shielding cavity according to the proposed impedance characteristics and transmission constants, and calculating the shielding effectiveness of the shielding cavity according to the equivalent model; and performing simulation verification on the node shielding effectiveness calculation method. The shielding effectiveness of the robot case is obtained through calculation, and the shielding effectiveness of the robot case is improved to enhance the survivability of the broken strand repairing robot.

This invention discloses a method, system, equipment, and medium for panoramic identification of short-circuit parameters in distribution networks based on multi-frequency disturbance excitation. It belongs to the field of power system condition monitoring and fault analysis technology. The method includes: designing and generating a composite disturbance signal; injecting the composite disturbance signal into the bus under test of the distribution network through a controllable current source, and acquiring time-domain waveform data of the injected current signal and the bus voltage; performing frequency domain transformation to separate and extract voltage and current phasors in the frequency domain; obtaining short-circuit impedance measurements at each frequency point using a first algorithm; and identifying equivalent circuit parameters using the short-circuit impedance measurements at several characteristic frequency points through a parameter fitting method. Compared to traditional single-frequency measurements that can only acquire single-point data, this method provides more comprehensive panoramic parameter information, accurately reflecting the impedance characteristics of the distribution network at different frequencies, and is suitable for modern distribution networks containing a large number of nonlinear loads and power electronic equipment.

The invention discloses an impedance coupon characterization method, an impedance coupon and a PCB in the field of PCB manufacturing impedance coupon design, and the method comprises the steps: obtaining the copper thickness of a continuous superposition layer to determine a power supply layer, and analyzing a copper-free region in the power supply layer to determine the arrangement type of a segmentation gap; determining a signal layer according to the power supply layer, obtaining an impedance line and a necking layer structure corresponding to the signal layer, and extracting a structure factor related to impedance; the impedance lines, the necking layers and the segmentation gaps are arranged on the impedance coupon according to corresponding factors, and combined design is carried out, so that the impedance coupon capable of representing the impedance characteristic of the signal layer under the segmentation gap superposition condition is constructed; according to the invention, through impedance coupon, the representativeness and reliability of the impedance test on the actual impedance state in the PCB can be improved.

The invention discloses a fault detection method and system for a driving circuit of an electronic circuit board, and relates to the technical field of electronic engineering. According to the fault detection method for the electronic circuit board driving circuit, impedance spectrum scanning, switch stress pulse and dynamic response test signals are injected into the electronic circuit board driving circuit in sequence, response signals are collected, and the impedance characteristic, the resonance mode and the dynamic performance of the circuit are analyzed. The capacitance value and the equivalent series resistance of a direct current bus capacitor are obtained through impedance analysis, the dominant resonant frequency and the damping ratio of a power loop are obtained through resonance mode analysis, and the phase margin of a control loop is obtained through dynamic performance analysis. According to the method, impedance, resonance and control parameters are extracted through multi-signal injection, fault diagnosis reliability and accuracy are improved through combined analysis, and stable operation of a system is guaranteed.

The application discloses a voltage source type energy storage wide frequency band negative resistance characteristic analysis method based on impedance splitting. The method is simplified based on a voltage source type energy storage impedance model, impedance characteristics of a simplified model in a wide frequency band range are analyzed, impedance frequency bands are divided according to characteristics of a voltage source type energy storage controller and the wide frequency band impedance characteristics, a medium frequency band negative resistance source is analyzed by using the impedance splitting method, and the voltage source type energy storage instability risk positioning method is improved, thereby providing a reference for improving small signal stability of the voltage source type energy storage.

According to one embodiment, a method performed by a wearable device worn on a first part of a user's body may comprise the operations of: receiving a radio frequency (RF) signal, for identifying a gesture performed through the user's body, from another wearable device, worn on a second part of the user's body, within a reference time interval through a communication circuit on the basis of a movement of the user's body; identifying first information about the strength of the received RF signal and second information, included in the received RF signal, about impedance characteristics of the other wearable device; recognizing a gesture, performed within the reference time interval according to the movement of the user's body, on the basis of the first information and the second information; and performing at least one function corresponding to the recognized gesture.