380 results about "Ac impedance" patented technology

A ripple voltage, caused by a voltage inverter, is superimposed on an output voltage provided by a fuel cell stack. This ripple voltage is sensed and used to determine an AC impedance of the fuel cell stack. The determined AC impedance can be correlated to a hydration state of the fuel cell stack.

The present invention takes the form of a current limiting apparatus and method for limiting current flow, induced when the level of an external signal is greater than an external signal threshold signal level, in a conductive loop formed by a medical device implanted within a living organism having electrically excitable tissue. The system includes an implantable pulse generator (IPG) system having a housing, a signal generator disposed in the housing that generates an electrical signal, and at least one lead extending from the housing to convey electrical signal to the patient. To limit the induced current flow, the IPG includes current limiting componentry, an impedance increasing element, and / or alternating current blocking elements. These components provide an alternating current impedance path to the electrical ground from a lead coupled to the capacitive element. Also disclosed are techniques for reducing the effective surface area of the current inducing loop caused by the IPG system.

A charge pump method and apparatus is described having various aspects. Noise injection from a charge pump to other circuits may be reduced by limiting both positive and negative clock transition rates, as well as by limiting drive currents within clock generator driver circuits, and also by increasing a control node AC impedance of certain transfer capacitor coupling switches. A single-phase clock may be used to control as many as all active switches within a charge pump, and capacitive coupling may simplify biasing and timing for clock signals controlling transfer capacitor coupling switches. Any combination of such aspects of the method or apparatus may be employed to quiet and / or simplify charge pump designs over a wide range of charge pump architectures.

Systems, apparatuses and methods for detecting internal cell faults using online and real-time sensing techniques, and providing an accurate and reliable early warning for the incoming failure of battery cells hours or days prior to failure. A system is configured to perform real-time and direct measurement of battery cell parameters of temperature, voltage, and AC impedance through online sensing. These parameters may be simultaneously processed using advanced probabilistic and / or fuzzy logic-based algorithms to provide an early warning for the incoming failure of battery cells in a battery pack. This technology may safeguard the LIB battery packs while allowing them to operate at or near 100% capacity in both transportation and stationary applications.

A light-emitting device and an illumination apparatus are disclosed. A plurality of LED elements are connected in series between positive and negative lines, and first bypass capacitor is connected in parallel to the LED elements respectively. Each series circuit of a predetermined number of LED elements is connected in parallel to second bypass capacitors. As a result, with the negative power line set as a grounding point, the AC impedance at connection points of the series circuit of the LED elements against the ground is reduced. Thus, the erroneous lighting or “flicker” of each LED which otherwise might be caused by an external noise is prevented.

A charge pump method and apparatus is described having various aspects. Noise injection from a charge pump to other circuits may be reduced by limiting both positive and negative clock transition rates, as well as by limiting drive currents within clock generator driver circuits, and also by increasing a control node AC impedance of certain transfer capacitor coupling switches. A single-phase clock may be used to control as many as all active switches within a charge pump, and capacitive coupling may simplify biasing and timing for clock signals controlling transfer capacitor coupling switches. Any combination of such aspects of the method or apparatus may be employed to quiet and / or simplify charge pump designs over a wide range of charge pump architectures.

A capacity maintenance ratio determination device includes an impedance measurement unit and a capacity estimation unit. An alternating signal is applied from a signal generator to a battery. Frequency characteristics of AC impedance are calculated by the impedance measurement unit based on a response signal output from the battery in response to the alternating signal. A feature frequency is determined from the calculated frequency characteristics. The capacity estimation unit includes a memory and a determination unit. A correspondence relationship among a temperature of the battery, the feature frequency and a capacity maintenance ratio is stored in the memory. The determination unit determines the capacity maintenance ratio of the battery based on the temperature of the battery detected by a temperature detector, the determined feature frequency and the correspondence relationship stored in the memory.

Four electrodes or three electrodes system are adopted in the invention. Carbon electrode is in sue for working electrode and auxiliary electrode for loading test current, and saturated calomel electrode is in use for reference electrode for testing response voltage. In testing, exchange membrane is placed in middle of connection hole corresponding to two electrolytic cells. Transverse resistance is measured by using AC impedence method. Conductivity of membrane is calculated out from thickness of membrane and area of the connection hole. The invented method prevents polarization issue occurred in DC test method is applicable to testing transverse conductivity of diaphragms used in other fuel cells and lithium ion cells.

A method of measuring a glycosylated protein proportion by an AC impedance method includes passing an AC voltage or AC to two inspecting electrodes; covering a solution containing glycosylated protein completely onto the inspecting electrodes; measuring an impedance value between the electrodes and calculating the difference between the impedance value and an impedance value of a solution without glycosylated protein by an AC impedance inspection device; comparing the impedance difference with AC impedance difference / glycosylated protein concentration to obtain the proportion of the glycosylated protein in the solution containing glycosylated protein. The solution without glycosylated protein includes a salt solution and a non-glycosylated protein; the proportion of glycosylated protein in the solution containing glycosylated protein refers to the proportion of glycosylated protein in the total quantity of protein in the salt solution; and the proportion of glycosylated hemoglobin of the total quantity of hemoglobin in the salt solution.

The invention relates to a fuel cell AC impedance on-line testing system and a measuring and controlling method thereof. The system comprises a program-controlled alternating current (AC) source, a blocking capacitor, a main controller, a CAN bus and a plurality of AC impedance testing units. Each AC impedance testing unit is used for detecting n chips of fuel cell AC impedances connected in series. The measuring and controlling method of the system has two working modes, which are a dynamic measuring and controlling mode and a static measuring and controlling mode. Under a dynamic measuring and controlling mode, when a fuel cell stack generates power, the main controller controlls the AC source and the AC impedance testing units through the CAN bus, measurement is carried out, measurement data is collected, such that AC impedance spectrums of all the single-chip fuel cells are obtained. Under the static measuring and controlling mode, when the fuel cell stack does not generate, the testing upon AC impedance of fuel cells with any number at a certain fixed frequency point is set manually. The system and the method provided by the invention are advantaged in simple circuit, high measurement precision, and high reliability. With the system and the method, real-time and high-precision testing requirements of fuel cell AC impedance can be satisfied.

The invention relates to a high-efficiency voltage stabilization comprehensive control method of an induction power transmission system, belonging to the technical field of radio energy transmission.The system consists of two closed-loop circuits: an optimal efficiency tracking control loop and a robust constant pressure control loop. The optimal efficiency tracking control loop calculates the efficiency expression by establishing an AC impedance model for the system circuit, obtains the optimal equivalent load, adds an impedance matching network at a secondary side, and adjusts the duty cycle of a converter so that the equivalent resistance of the rectified output reaches the optimal load value to realize optimal efficiency tracking. The robust constant voltage control loop sends a difference between a load acquisition voltage and an input reference voltage into a robust controller by establishing a parameter perturbation model of the system to obtain a constant voltage of a high-frequency full-bridge inverter of a phase-shifted angle control primary side. The optimal efficiency tracking control and closed-loop robust control of an active impedance matching network can meet the multi-performance requirements of optimal efficiency and constant output voltage.

The invention discloses a three-electrode battery. The three-electrode battery comprises an outer shell, a positive electrode, a negative electrode, diaphragms, electrolyte, a reference electrode and a nickel electrode lug; the reference electrode is arranged between the positive electrode and the negative electrode; the diaphragms are arranged respectively between the positive electrode and the reference electrode and between the reference electrode and the negative electrode; the whole three-electrode battery is packaged in the outer shell; and the outer shell is filled with the electrolyte. One end of the reference electrode is a naked copper wire which is completely arranged between the positive electrode and the negative electrode, and the three electrodes are subjected to lithium plating before an AC impedance test; the other end of the reference electrode is a varnished wire; one portion of the varnished wire is immerged in the electrolyte, and the other portion of the varnished wire is located outside the positive electrode and the negative electrode and extends to the outer side of the outer shell to be connected with the nickel electrode lug; and the nickel electrode lug is fixed with the outer shell. The invention also discloses a preparation method of the three-electrode battery. The three-electrode battery has the advantages that the signal interference resistance is strong, the manufacturing cost is low, transmission of the lithium ions between the positive electrode and the negative electrode is guaranteed, in-situ monitoring for the electric potential of the positive electrode, the electric potential of the negative electrode and the impedance of the lithium ion battery in a use process is carried out, the detection accuracy is improved obviously, and the detection efficiency is improved.

An ion conductor includes a mixture including an electrolyte including a salt including inorganic or organic pairs of negative and positive ions, and a low-molecular liquid crystal material. Further, an impedance of the ion conductor varies in accordance with an increase of a voltage applied to the ion conductor due to an orientation response of the low-molecular liquid crystal material, the impedance being determined by an AC impedance method.

The invention provides a flaky titanium carbide-loaded manganese dioxide composite material, which is mainly applied to a super capacitor electrode material, and belongs to the field of composite materials and the technical field of super capacitors. With Ti<3>AlC<2> powder as a raw material, Ti<3>C<2>T<x> with a two-dimensional flaky structure is formed after Al is etched away through HF; and in-situ growth is carried out on a two-dimensional layered titanium carbide surface by potassium permanganate and the Ti<3>C<2>T<x>, thereby obtaining the composite material loaded with a manganese dioxide thin film and a few of manganese dioxide particles on the flaky titanium carbide surface. The composite material is excellent in capacitive performance; the measured specific capacity can reach 256F / g in 0.5M K<2>SO<4> electrolyte; the specific capacity retention rate reaches 92% after 1,000 cycles; and meanwhile, an AC impedance test demonstrates that the material is extremely low in impedance, has the advantages of good safety, high reliability, sufficient energy and the like and has a broad commercial application prospect.

The invention discloses an alternating-current impedance analytical method of an electrochemical energy storage device. The method comprises steps as follows: an integrated DC / DC converter is provided and comprises a first DC / DC converter, a disturbance source and a controller, and the first DC / DC converter is connected with the disturbance source in parallel; the controller switches on the disturbance source and controls the disturbance source to generate a current disturbance signal simultaneously; the output current of the electrochemical energy storage device is disturbed by the current disturbance signal; the disturbed output current and the output voltage of the electrochemical energy storage device are detected; the impedance corresponding to the frequency of the current disturbance signal is calculated according to the current disturbance signal as well as the disturbed output current and the output voltage, the frequency of the current disturbance signal is changed, and the output current of the electrochemical energy storage device is disturbed again to obtain the alternating-current impedance spectrum of the electrochemical energy storage device.

The invention discloses a method for diagnosing an interturn short circuit of a rotor winding. The method comprises the following steps of: giving a judgment that a rotor winding has interturn stability short circuit fault through a rotor alternating current impedance test; then judging whether the rotor winding has the interturn instability or stability short circuit fault or not by combining a voltage oscillation wave test; and blending the results of the alternating current impedance test and the oscillation wave test to analyze and find out the position of a short circuit point so as to process the fault in time and recover the rotor winding to be insulated. The invention has the characteristics of simple and convenient measurement, low cost and good practical effect and can be used for detecting and diagnosing the interturn faults of rotors of steam turbine generators, water wheel generators and electric motor generator in a static state.

Defects in components in ICs which may cause circuit failures during operation of the IC are often difficult to detect during and immediately after fabrication of the IC by DC test methods. A method of testing components to detect such defects using AC Impedance Spectroscopy is disclosed. Data may be analyzed using Nyquist plots and Bode plots. Nyquist plots of typical defect types are disclosed. Components may include MOS transistor gate structures, contacts, vias and metal interconnect lines. Components tested may be contained in integrated circuits or in test circuits. Integrated circuits containing components tested by AC Impedance Spectroscopy may be partially fabricated or deprocessed after fabrication.

The invention provides a lithium ion battery failure analysis method based on an alternating current impedance method. The safety performance of a lithium-ion battery has attracted much attention, anda negative electrode of the lithium ion battery is easily subjected to lithium evolution under the abuse condition, so that a lithium dendritic crystal is formed, and thermal runaway or even explosion of the battery is caused. According to the lithium ion battery failure analysis method based on the alternating current impedance method provided by the invention, an electrochemical alternating current impedance testing method is adopted, a relationship between an alternating current impedance spectrum signal and the internal environment of the battery is analyzed, the SEI film resistance change can be analyzed from an alternating current impedance spectrum, and therefore the state of short circuit in the dendritic crystal of the battery can be quickly and accurately predicted without damaging the battery, thereby evaluating the service life and the safety of the battery.

When the operation point of a DC / DC converter, which steps up / down the output voltage of a fuel cell stack, is in a range of reduction in response capability and further there is issued a request of determining an AC impedance, a controller switches numbers of the drive phases of the DC / DC converter to determine an AC impedance of the fuel cell stack. If the operation point of the DC / DC converter is in the range of reduction in response capability and further the precision of determining the AC impedance is reduced, then the determination of AC impedance in the range of reduction in response capability is inhibited and the switching of the phases of the DC / DC converter is implemented, thereby causing the operation point of the DC / DC converter to be out of the range of reduction in response capability, with the result that the precision of determining the AC impedance can be raised.

The invention provides a lithium battery AC impedance spectrum online synchronous test method and device. The method is characterized by obtaining a current discrete sampling sequence and a voltage discrete sampling sequence through current excitation signals and voltage response signals of a lithium battery; then, calculating a cross-correlation function of the current discrete sampling sequence and the voltage discrete sampling sequence through a Wiener-Hopf equation, and serving the cross-correlation function as a time domain impulse response function of the lithium battery; then, carrying out Fourier transform on the time domain impulse response function to obtain frequency response of the lithium battery; and adjusting the order of a signal generator to obtain lithium battery AC impedance spectrum in different frequency bands. The method and device can realize synchronous test of a plurality of AC frequency impedance of the lithium battery; frequency response of the lithium battery can be obtained through the impulse response function; the required priori knowledge is less; identification can also be carried out very well under the condition that noise and signal-to-noise ratio are rather small; the correlation function can be obtained through the Wiener-Hopf equation; and the device and method have higher anti-jamming capability.

The invention discloses a constant-current output type two-way wireless power transmission system for a composite resonant network and a design method of the system. The system is formed by connecting a primary side DC power supply, a primary side choke inductance, a primary side high-frequency switching network, a primary side parallel compensation capacitor, a primary side series compensation capacitor, a loose coupling transformer, a secondary side series compensation capacitor, a secondary side parallel compensation capacitor, a secondary side high-frequency switching network, a secondary side choke inductance and a secondary side DC power supply in sequence. The system is characterized in that a novel circuit topology is provided; through carrying out parameter design on a primary side compensation mechanism, the loose coupling transformer and a secondary side compensation mechanism, the system is of a mirror symmetry structure, so that the constant-current output of the wireless power transmission system is realized while the two-way transmission of the energy is also realized. The system and the method have the beneficial effects that the complicated closed-loop control is not needed when the system is designed, the system design indexes can be met based on an AC impedance method through parameter design, the system structure is simplified, and the system stability is improved.

The invention discloses an alternating current (AC) impedance spectroscopy automatic testing device of positive temperature coefficient (PTC) thermistor. The device comprises an electric heating oven for holding a sample, a temperature control and protection circuit for maintaining the electric heating oven at a constant temperature and preventing overcurrent, an impedance measuring circuit for measuring the sample impedance, and a master control machine connected with two circuits via a CAN bus respectively and used for receiving a user instruction and controlling the two circuits to accomplish measurement. The impedance measuring circuit in the invention is based on high-speed synchronous data acquisition and digital signal processing technology, satisfies the measurement requirements for high precision, wide measurement range and wide frequency band, and has features of small volume, low cost and convenient operation. Data communication among the temperature control and protection circuit, the impedance measuring circuit and the master control machine is realized via CAN buses, to achieve good real-time property and high reliability. The invention can ensure constant-temperature testing environment, carries out multi-frequency point scanning measurement to the AC impedance of the tested sample, and realizes full automatic testing of impedance-temperature characteristics of the PTC thermistor under different frequencies.

The invention discloses preparation of a three-dimensional graphene manganese dioxide nano-composite modified electrode and a capacitive property test method thereof. An ionic liquid modified electrode is prepared firstly, and then three-dimensional graphene and manganese dioxide nanomaterial are electrodeposited on the surface of the ionic liquid modified carbon paste electrode by utilizing a constant potential method so that a three-dimensional graphene manganese dioxide nano-composite modified carbon paste electrode is obtained. The three-dimensional graphene manganese dioxide nano-composite modified electrode acts as a working electrode, a platinum sheet acts as an auxiliary electrode and a saturated calomel electrode acts as a reference electrode, and capacitive property of three-dimensional graphene manganese dioxide nano-composite material is tested by applying a cyclic voltammetry, an AC impedance method and a constant current charge and discharge method. The three-dimensional graphene manganese dioxide nano-composite modified electrode is simple in preparation method, high in single electrode capacitance and great in cycle performance so as to be suitable for rapidly testing capacitive property of super-capacitor electrode material.

The invention discloses a nondestructive detection method for lithium separation of a lithium ion battery. The detection method comprises the following steps of a charging process of a to-be-detectedbattery, an electrochemistry stimulation process of the to-be-detected battery and an analyzing process of the to-be-detected battery. In the electrochemistry stimulation process, according to conditions that alternating-current impedance of the lithium ion battery changes with time, whether or not the lithium separation phenomenon occurs in the battery is judged, and when the phenomenon that thealternating-current impedance is subjected to phase step with time occurs, it can be seen that in the charging process, the to-be-detected lithium ion battery is subjected to lithium separation. The detection method belongs to nondestructive detection and can quickly acquire experiment parameters and accurately reflect the lithium separation conditions in the battery. The detection method is suitable for judging charging conditions of the lithium ion battery, determining charging parameters of the maximum charging current, the maximum charging voltage and the like, and determining the parameter range of external conditions of temperature and the like in the charging process under the circumstance that the lithium separation phenomenon does not occur. On the premise of not influencing performance of the battery, quick charging for the battery is completed through the determined charging parameters.

A new, extremely sensitive, and rapid electronic detection method for direct detection of hybridized genomic targets to specific probes on the microarray is proposed. The method consists of fast electronic accumulation of the DNA target on a particular electrode site at the micro-electrode array, sequential electronic hybridization of oligonucleotide labeled metallic (nano)particles on the target DNA and monitoring the electrochemical AC impedance changes at the electrode site. The method is enhanced by electroplating over the DNA target which serves as the metallization template and over the particles which provide seeds for rapid electroplating. The AC impedance changes are monitored during the electroplating over the DNA target and between the array electrodes sites. The signal in the absence and presence of the target DNA is a difference between “no connection” and a “short” between the array electrodes

The invention discloses a battery charging discharging current limited value calculating method and a battery charging discharging current limited value calculating device. The battery charging discharging current limited value calculating method comprises the following steps: acquiring a current charge state and current test temperature of a battery unit of a battery pack; calculating current AC impedance and current compensation voltage according to the current charge state, the current test temperature, the predetermined AC impedance relation table, and the predetermined compensation voltage relation table; acquiring an estimation battery voltage calculating formula according to the current charge state, the current AC impedance, and the current compensation voltage; determining a plurality of charging current values and a plurality of discharge current values, and calculating the corresponding estimation battery voltage values respectively according to the estimation battery voltage calculating formula; and calculating battery charging discharging current limited values according to a plurality of charging current values, a plurality of discharging current values, and the corresponding estimation battery voltage values. The battery charging discharging current limited value calculating method is advantageous in that the battery charging discharging current limited values can be calculated in a real-time manner during the use of the battery, and the calculating precision of the battery charging discharging battery limited values can be improved.

The invention discloses a method for detecting single electrode potential of a battery. The method comprises the following steps: an AC impedance test is used for acquiring AC impedance spectrums of a positive electrode / negative electrode, a positive electrode / reference electrode and a negative electrode / reference electrode of the battery in different states of charge (SOC) and at different temperatures; an equivalent circuit, a positive electrode equivalent circuit and a negative electrode equivalent circuit of the total battery are respectively used to fit the AC impedance spectrums of the positive electrode / negative electrode, the positive electrode / reference electrode and the negative electrode / reference electrode, and a related three-dimensional mapping table between equivalent impedance of the positive electrode and the negative electrode and the SOC and the temperature is obtained; the current electrode equilibrium potential is obtained according to the SOC of the battery and a equilibrium potential curve; and the single electrode potential is obtained according to the electrode equilibrium potential, charging / discharging current sum of the battery and the three-dimensional mapping table. The electrode potential of a common battery can be directly and conveniently measured, and accuracy of the measurement result is improved. The invention also provides a system for detecting single electrode potential of a battery.