428 results about "Impedance spectrum" patented technology

The ability of an ultrasonic system to sweep and lock onto a resonance frequency of a blade subjected to a heavy load at startup is improved by applying a high drive voltage or a high drive current while systematically increasing the level of the applied signal. Increasing the drive signal to the hand piece results in an improved and more pronounced “impedance spectrum.” That is, under load, the increased drive signal causes the maximum phase margin to become higher and the minimum/maximum impedance magnitude to become more pronounced. Increasing the excitation drive signal to the hand piece/blade at startup significantly alleviates the limiting factors associated with ultrasonic generators, which results in an increase of the maximum load capability at startup.

Methods and systems for calibration of RFID sensors used in manufacturing and monitoring systems are provided. The methods include measuring impedance of an RFID sensor antenna, relating the measurement of impedance to one or more parameters (such as physical, chemical and biological properties), computing one or more analytical fit coefficients, and storing the one or more analytical fit coefficients on a memory chip of the RFID sensor. Measuring impedance of the RFID sensor may comprise measuring complex impedance which involves measuring complex impedance spectrum, phase angle and magnitude of the impedance, at least one of frequency of the maximum of the real part of the complex impedance, magnitude of the real part of the complex impedance, zero-reactance frequency, resonant frequency of the imaginary part of the complex impedance, and antiresonant frequency of the imaginary part of the complex impedance. Also provided are manufacturing or monitoring systems comprised of an RFID sensor wherein the RFID sensor comprises, a memory chip, an antenna, and a sensing film wherein analytical fit coefficients are stored on the memory chip to allow calibration of the RFID sensor. Also provided are manufacturing or monitoring systems comprised of an RFID sensor wherein the RFID sensor comprises, a memory chip, an antenna, and a complementary sensor attached to the antenna where the complementary sensor in a pre-calibrated fashion predictably affects the impedance of the antenna.

Provided with a method of measuring battery capacity by impedance spectrum analysis, which is to measure a characteristic impedance spectrum of primary and secondary batteries and determine the battery capacity the method including the steps of: (1) measuring the characteristic impedance spectrum of a battery in a predetermined frequency region; (2) determining a parameter from the measured impedance spectrum; (3) monitoring in advance the correlation between the determined parameter and the battery capacity measured by a real-time discharge technique; and (4) determining the battery capacity from the characteristic impedance spectrum of a battery having an unknown capacity based on the monitored correlation.

An apparatus and methods for detecting and identifying faults in a fuel cell are disclosed. An impedance spectrum relating to the fuel cell is compared with fault criteria to identify fault conditions in the fuel cell. A time-varying current is drawn from the fuel cell at a selected frequency and the impedance of the fuel cell at the frequency is measured. This may optionally be repeated at a range of frequencies or at combinations of frequencies to provide an impedance spectrum across the range of frequencies. The fault criteria identify one or more fault conditions that may be identified by comparing the measured impedance spectrum to the fault conditions.

The invention provides a parameter obtaining method of a single lithium ion full battery, and belongs to the field of new energy research. The method comprises the following steps that 1) a mathematical electrochemical impedance spectrum model of the lithium ion battery is established; 2) an electrochemical impedance spectrum of the single lithium ion full battery to be measured is measured actually; and 3) according to the established mathematical model, parameters of the actually measured electrochemical impedance spectrum are identified according to frequency ranges, and anode and cathode parameters of the single lithium ion full battery to be measured are obtained. Aimed at the defect that parameters cannot be identified effectively when a present semi-battery model is used for a full battery, characteristics of the electrochemical impedance spectrum of the lithium ion battery are combined, a manner of parameter identification according to the frequency ranges is used, and anode and cathode model parameters of the lithium ion full battery can be obtained rapidly and accurately. The method of the invention can be used for gaining mechanism analysis, SOC estimation and life prediction of the lithium ion battery.

The invention relates to a method for determining an aging condition of a battery cell. The method has the following steps of a) providing a battery cell, b) recording an impedance spectrum of the battery cell, c) determining an evaluation quantity based on the measured impedance spectrum, and d) determining an aging condition of the battery cell based on a comparison of the evaluation quantity to a reference value.

A spectrometer for measuring the complex impedance spectrum of tissue comprises: a multi-frequency excitation current generator; a demodulation signal generator; two identical amplification/demodulation circuits; an A/D converter; and a microprocessor for signal processing. In use, the current generator excites the tissue sample and a series-connected reference impedance. The voltages generated in the tissue and reference are measured, demodulated, and digitized in parallel using the demodulation signal generator, the two amplification/demodulation circuits, and the A/D converter. Demodulation is done using the same demodulation signal generated at a frequency with a preset difference from the excitation signal, which allows measurements to be made at a low frequency independent of the excitation frequency. The microprocessor then calculates the complex impedance spectrum in relation to the reference signal. Because the measurements are relative, they are independent of both the excitation current amplitude of the phase of the excitation and demodulation signals.

A small, lightweight, portable, and inexpensive self-processing integrated damage assessment sensor (SPIDAS) that may be temporarily or permanently attached to a structure for structural health monitoring is provided. The SPIDAS device employs an electromechanical impedance measuring method to directly measure the high-frequency local impedance spectrum of the structure, process the electromechanical impedance data, and issue structural health reports that the device may transmit over a wireless connection.

A lithium ion battery internal health feature extraction method based on an impedance spectrum, and relates to the new energy research field; an existing method uses an EIS to analyze and estimate a SOH, wherein the EIS is long in measuring time, and cannot realize online measurements; the lithium ion battery internal health feature extraction method comprises the following steps: building a lithium ion battery electrochemistry impedance spectrum mathematics model; fast measuring a lithium ion battery electrochemistry impedance spectrum, and obtaining the lithium ion battery electrochemistry impedance spectrum; using the lithium ion battery electrochemistry impedance spectrum mathematics model to identify the lithium ion battery electrochemistry impedance spectrum parameters respectively under high, medium and low frequency stages, thus obtaining the lithium ion battery model parameters; periodically measuring the electrochemistry impedance spectrum of the aged lithium ion battery, using the lithium ion battery electrochemistry impedance spectrum mathematics model to identify the lithium ion battery electrochemistry impedance spectrum parameters of the aged lithium ion battery, thus obtaining the model parameter changing rules in the lithium ion battery aging process, and serving as the features that evaluate the battery health states. The lithium ion battery internal health feature extraction method is used for evaluating the battery health states.

The invention discloses an online proton exchange membrane fuel cell fault diagnosis method based on an impedance spectrum. The method includes: Firstly, establishing an electrochemical equivalent circuit model of the proton exchange membrane fuel cell; performing measuring to obtain an electrochemical impedance spectrum of the proton exchange membrane fuel cell; fitting and solving parameters inthe electrochemical equivalent circuit model by using an electrochemical impedance spectrum; and then selecting a part of parameters as classification characteristics, carrying out classification processing on the proton exchange membrane fuel cells by using a fault diagnosis algorithm based on a binary tree support vector machine, and diagnosing faults such as membrane dryness, water logging andair starvation which easily occur in the proton exchange membrane fuel cells. The problem that fault detection is difficult in the operation process of the proton exchange membrane fuel cell is solved, the electrochemical impedance spectroscopy technology is applied to on-line operation monitoring and fault diagnosis of the fuel cell, and the reliability and durability of the cell can be improved.

In one embodiment a method for sensor reader calibration comprising: performing a calibration of a sensor reader wherein the calibration comprises open circuit calibration, a short circuit calibration, and a load circuit calibration, or any combination thereof in any succession; enabling connection of a pickup coil to the sensor reader to measure a sensor response; and applying a baseline correction to the sensor response, wherein the baseline correction is obtained utilizing measurements from the calibration step. In a further embodiment, a method for sensor response calibration incorporating environmental correction comprising: measuring a first resonance impedance spectrum of the sensor with a first applied power to the pickup coil; measuring a second resonance impedance spectrum of the sensor with a second applied power to the pickup coil; and applying a correction to the sensor response corresponding to the respective measured first and second resonance impedance spectrum to mitigate for environmental parameters.

A method for dynamic characterization of an electrochemical system (such as a lithium-ion battery) is provided, comprising exciting an electrochemical system with a plurality of double-pulse sequences, each comprising a constant-current discharge pulse, a constant-current charge pulse having the same pulse width and pulse amplitude, and a zero-current period between the pulses; and calculating an impulse response, using a recursive or matrix-based method, to dynamically characterize the electrochemical system. A constant state-of-charge is maintained in the electrochemical system. Therefore the signal-to-noise ratio is high due to the repetition of the driving sequence. This method may be employed for on-line determination of the impedance spectrum of an electrochemical system, since the cycling profile can be easily integrated into charge/discharge profiles. Batteries (and other devices) can be diagnosed at high speed and with high accuracy. The double-pulse sequence is robust for fairly noisy systems.

Provided with a method of measuring battery capacity using parameters obtained from a voltage response signal of a current waveform or an impedance spectrum generated thereof where the method includes the steps of: measuring voltage response signals based on a current waveform applied to a primary or secondary battery; obtaining parameters of an equivalent circuit composed of model parameters such as resistors, capacitors and transmission lines either directly from voltage response or after its conversion to frequency dependent impedance; and determining the unknown battery capacity from the voltage response characteristics based on a correlation between the measured capacity and the model parameters, which correlation is previously determined by a real-time discharge method, thereby takes a shorter time than a real-time discharge method and delivering efficiency and reliability in determining model parameters of an equivalent circuit which are in close correlation with the charge/discharge condition of the battery.

The invention discloses biological tissue multiple frequency impedance measuring method and measuring apparatus thereof, wherein the linear transformation iterate method of curve fitting is first applied to the extraction of biological tissue impedance model parameter, which can realize accurate matching only through limited frequencies. The measuring apparatus includes a single chip machine for data acquisition, a direct digital frequency synthesizer, a voltage control constant-current source, a current electrode, a voltage measurement and reference signal magnification and filtering circuit, an amplitude discrimination device, a shaping and phase detector, a PC and an isolated serial line interface.

A method and apparatus for determining spatial locations of defects in a material are described. The method includes providing a plurality of electrodes in contact with a material, applying a sinusoidal voltage to a select number of the electrodes at a predetermined frequency, determining gain and phase angle measurements at other of the electrodes in response to applying the sinusoidal voltage to the select number of electrodes, determining impedance values from the gain and phase angle measurements, computing an impedance spectrum for an area of the material from the determined impedance values, and comparing the computed impedance spectrum with a known impedance spectrum to identify spatial locations of defects in the material.

Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. The time profile of this signal has a duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time record by rectifying relative to the sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.