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160 results about "Impedance properties" patented technology

Foreign body detection method and system based on impedance characteristic

The invention provides a foreign body detection method and system based on an impedance characteristic. The method comprises the steps that a detection coil is laid in an area to be detected, wherein the detection coil is connected with a capacitor element to form a resonant circuit, and a high frequency carrier signal is loaded on the resonant circuit; a resonant current signal on the resonant circuit is collected; other induction signals outside the frequency band of the high frequency carrier signal are filtered out; and finally, amplitude and phase analysis is carried out on the filtered resonant current signal to determine whether a foreign body is in the area to be detected. The method has the advantages that the impedance change of the detection coil is correspondingly acquired by detecting the change of the phase and amplitude of the resonant current signal, so as to judge whether a foreign matter exists. The method has the advantages of low cost and good effect. The original system is changed less. Especially for a wireless power transmission system, without affecting the efficiency of the original system, the method and system can be well adapted to foreign body detection in a variety of magnetic fields to improve the safety of the wireless power transmission system.
Owner:CHONGQING UNIV

Measuring circuit and a method for determining a characteristic of the impedance of a complex impedance element for facilitating characterization of the impedance thereof

A single chip integrated circuit measuring circuit (1) for determining a characteristic of the impedance of an external complex impedance circuit (2) for facilitating characterization of the impedance of the complex impedance circuit (2) comprises a signal generating circuit (7) for generating a variable frequency stimulus signal for applying to the complex impedance circuit (2). A first receiving circuit (10) receives a response signal from the complex impedance circuit (2) in response to the stimulus signal and conditions the response signal. A first analog-to-digital converter (68) converts the conditioned response signal to a first digital output signal, which is read from the first analog-to-digital converter (68) through a first digital output port (14). The response signal from the complex impedance circuit (2) is a current signal, and a current to voltage converter circuit (64) converts the response signal to a voltage signal. A first RMS to DC level converting circuit (70) converts the AC voltage of the response signal to a DC voltage level, and a fourth multiplexer (67) selectively applies the voltage response signal or the DC voltage level signal to the first analog-to-digital converter (68), depending on whether it is desired that the first digital output signal should be indicative of the phase shift or amplitude change in the response signal relative to the stimulus signal. A second receiving circuit (20) receives the stimulus signal, and similarly converts the stimulus signal to a second digital output signal for facilitating comparison of the response signal with the stimulus signal.
Owner:ANALOG DEVICES INC

Ripple analysis-based electrolytic capacitor life calculation method

The invention relates to the technical field of power electronics, in particular to a ripple analysis-based electrolytic capacitor life calculation method. The method comprises the steps of solving current ripples of an electrolytic capacitor under different frequencies by utilizing double Fourier series, and solving electrolytic capacitor life in combination with impedance characteristics of the electrolytic capacitor and an inner temperature rise-based electrolytic capacitor model. Specifically, the method comprises the steps of A, calculating an effective value of each harmonic current in a buck circuit; B, giving out the electrolytic capacitor model and performing calculation through the effective value of the harmonic current and equivalent series resistance (ESR) of the electrolytic capacitor at a harmonic frequency by utilizing an iterative algorithm to obtain an inner temperature rise of the electrolytic capacitor; and C, substituting the inner temperature rise of the electrolytic capacitor into an electrolytic capacitor life formula and performing calculation to obtain the electrolytic capacitor life. According to the method, the electrolytic capacitor life model is combined with system parameters, so that the influence of inductance in a main circuit on the electrolytic capacitor life is analyzed; and the life calculation of the electrolytic capacitor is closely combined with the impedance properties of the electrolytic capacitor, so that the electrolytic capacitor life can be accurately solved.
Owner:WUHAN UNIV

Digitized intelligent ultrasonic power source and use method thereof

The invention discloses a digitized intelligent ultrasonic power source and a use method thereof. A PWM (Pulse Width Modulation) drive pulse signal is directly produced by a microprocessor and is adjusted by a rear-level circuit to be used for driving an ultrasonic transducer; a voltage adjustable power source is adjusted, and the output power of the ultrasonic power source is controlled; the current of a power frequency mains supply and the voltage of the voltage adjustable power source are monitored in real time, and the work state of the ultrasonic power source is adjusted; the voltage of an impedance matching circuit and the current of a resonance matching circuit are sampled in real time, and the frequency of the PWM drive pulse signal is dynamically adjusted through analyzing the impedance characteristic by the microprocessor so as to realize a dynamic matching process, ensure that the transducer always works at a resonance point and output the maximal available power. According to the digitized intelligent ultrasonic power source and the use method thereof, the ultrasonic power is adjustable, the matching mode is simple, the precision is higher, a circuit is simple, the safety and the reliability are realized, the cost is low, and the application prospect is wider.
Owner:HOHAI UNIV CHANGZHOU

High voltage isolating switch power and a plurality of output isolated switch power systems

The invention belongs to the field of power electronics and aims at providing a high voltage isolating switch power and a plurality of output isolated switch power systems. The switch power is inputted by AC power sources, inputted into a filter capacitor in parallel after being isolated and rectified by a transformer to change the impedance property, and then outputted by a conventional high frequency switch convertor; and the regulation direction of the switch power is opposite to the conventional direction. Output is divided into a voltage mode and a current mode; and an energy storage value of an output filter capacitor or inductance is higher than that of an input filter capacitor. The circuit and control method adopted by the voltage isolating switch power and the plurality of outputisolated switch power systems have the characteristics of compact structure, simple circuit, high working efficiency and low mutual interference among a plurality of auxiliary power sources, which are especially applicable to distributed auxiliary power supply needing high voltage and superhigh voltage insulated isolation, and can be applied in high voltage power electronic equipment. The high voltage isolating switch power and the plurality of output isolated switch power systems can also directly obtain electric energy from transmission lines of a power system, and assist to supply power for the power electronic equipment in an intelligent grid system.
Owner:ZHEJIANG UNIV
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