287 results about "Voltage oscillation" patented technology

An electric musical instrument transducer contains one or more air gapped parallel plate variable capacitors. Each variable capacitor in the transducer has one plate that comprises, covers, or is embedded within an acoustically emitting vibrating surface on a musical instrument (such as a drumhead or soundboard) while the other plate is a rigid surface held a fixed distance away. When the instrument is played, the vibrating surface causes vibrations directly (without using airborne sound as an intermediary) in the non-fixed plates of the variable capacitors, thus causing time-varying voltage oscillations in the variable capacitors that directly reflect the vibrational state, and therefore the sound, of the instrument. These voltage oscillations are then converted to signals that can be used by audio recording and amplification equipment.

A capacitive electric musical instrument vibration transducer contains one or more parallel plate variable capacitors. Each variable capacitor contains one vibrating variable capacitor plate, an electrically conducting surface that comprises, covers, or is embedded within an acoustically emitting vibrating surface on a musical instrument (such as a drumhead or soundboard), and one fixed variable capacitor plate comprising a rigid electrically conducting surface held a fixed distance away. When the instrument is played, the vibrating surface causes vibrations directly (without using airborne sound as an intermediary) in the vibrating variable capacitor plates, thus causing time-varying voltage oscillations in the parallel plate variable capacitors reflecting the vibrational state, and therefore the sound, of the instrument. An electric circuit in the transducer converts these voltage oscillations into the same kinds of signals produced by microphones and magnetic pickups.

A digital temperature sensing device uses temperature depending characteristic of contact resistance of a MOS transistor and a self-refresh driving device adjusts its self-refresh period depending on temperature using the digital temperature sensing device. The self-refresh driving device includes a first reference voltage generating unit for generating a reference voltage robust to temperature, the first reference voltage generating means being formed with a plurality of MOS transistors, the number of source contacts of the MOS transistors being adjusted such that variation of saturation current through source-drain is compensated for; a second reference voltage generating unit for generating a second reference voltage sensitive to temperature; a level comparator for comparing the first reference voltage with the second reference voltage; and an oscillator for generating a clock signals having differing period depending on the output signal of the level comparator.

The invention provides a soft switching conversion device based on a flyback converter. On the basis of the conventional Flyback converter power topology, a clamp branch consisting of a controllable power clamper tube and a clamp capacitor is connected to a drain end of a main power tube in series; a primary side chip of the conversion device receives information such as the peak excitation current, the valley bottom excitation current and the maximum voltage of switching nodes of a converter power loop and generates ideal drive dead time varying with an input voltage and a load condition to control the main power tube and the clamper tube, so that the voltage oscillation of the drain end of the power tube caused by leakage inductance can be completely eliminated. Owing to the basically loss-free soft switching technology of the MOS tube active clamp, the stable clamp voltage value and the primary-side and auxiliary-side full working conditions, the device can work at a high frequency(> 1MHz) and can greatly increase the power density of a power adapter when being applied to the adapter.

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.

The invention relates to a method of operating a spin-transfer torque structure to generate voltage oscillations, said structure comprising a first layer of magnetic material having a fixed magnetization vector, a spacer of non magnetic material and a second layer of magnetic material having a free magnetization vector. The method includes the application of a current (jop) through said structure and a magnetic field (Hext) in the plane of the second layer. It makes use of a region of bistability and hysteretic behaviour to trigger and stop the voltage oscillations.

The present invention discloses a system and method for soft starting of an isolation direct-current converter applied to a direct current distribution network. After a direct-current converter is started, the H-bridge output square-wave voltage duty ratio of an input side is gradually increased from 0 to 0.5 according to a ramp function, and the time of setting the duty ratio from 0 to 0.5 is a starting time; after the direct-current converter is started, the H-bridge output square-wave voltage duty ratio of an output side is always 0.5, and the direct-current converter is started, in the starting time, output given voltage is gradually increased from 0 to a rated value according to the ramp function, and the changing of the output given voltage is consistent to the changing of the H-bridge output square-wave voltage duty ratio of the input side. Through cooperation control of the two methods, the current impact and direct voltage oscillation are effectively inhibited when starting, the system has a good anti-interference capacity and does not need additional circuits and starting resistors, and the starting logic is simple.

A method, device and computer program product for providing improved control of power or voltage oscillation damping in a power transmission system. The device includes a magnitude obtaining element configured to obtain an instantaneous magnitude of a signal representing a deviating oscillation in at least one element of the power transmission system, a slope investigating element configured to determine the rate of change of the signal, and a first processing block including an integrating element configured to integrate the instantaneous magnitudes with an integrating factor that is based on the determined rate of change. The first processing block is further configured to form a phase compensation angle based on the integrated instantaneous magnitude for use in a damping control signal generating unit in order to provide power or voltage oscillation damping of the system.

A plasma generator includes a chamber for confining a feed gas. An anode is positioned inside the chamber. A cathode assembly is positioned adjacent to the anode inside the chamber. A pulsed power supply comprising at least two solid state switches and having an output that is electrically connected between the anode and the cathode assembly generates voltage micropulses. A pulse width and a duty cycle of the voltage micropulses are generated using a voltage waveform comprising voltage oscillation having amplitudes and frequencies that generate a strongly ionized plasma.

The invention discloses a device and a method for controlling a synchronous rectifier. The conversion rate of the switching voltage across the two ends of a secondary switch is detected in order to prevent the secondary switch from being triggered falsely due to switching voltage oscillation. The circuit includes a secondary switch coupled to an energy storage element, and a secondary control circuit. The secondary control circuit receives the switching voltage across the two ends of the secondary switch and a conversion rate threshold adjustment signal, and outputs a secondary switch control signal to control on-off of the secondary switch. When the conversion rate of the switching voltage is lower than a preset conversion rate threshold, the secondary switch control signal makes the secondary switch switched off.

The invention discloses a reverse blocking type IGBT and a manufacturing method therefor, and belongs to the technical field of a power semiconductor device. By introducing a floating P type body region on one side of a trench gate and introducing a trench collector structure in a collector region and a field stop layer, the positive breakdown voltage of a device is improved without influencing the threshold voltage and switch-on of an IGBT device; the gate-collector capacitance is lowered, and adverse influence caused by a Miller effect can be relieved; the overall gate capacitance is lowered, the switching speed of the device is improved, the switching loss of the device is lowered, and the compromising relation between forward switch-on voltage drop and switch-off loss of the conventional CSTBT device is improved; the problems of current, voltage oscillation and EMI in the device starting dynamic process can be avoided, and device reliability is improved; the current carrier enhancement effect at the emitter end of the device is improved, the current carrier concentration distribution in a drift region can be improved, and compromising between forward switch-on voltage drop andswitch-off loss can be further improved; and the reverse breakdown voltage of the device is improved, and high forward characteristic of the device is ensured while excellent reverse blocking performance is obtained.

Disclosed herein are methods, systems, and devices for identifying a location of a fault in a hybrid high voltage direct current (HVDC) transmission system having a ground or underground cable section and an overhead line section. Some methods comprise determining whether a characteristic voltage oscillation is present at a cable side terminal of the HVDC transmission system, and in response, determining that the fault is located in the overhead line section. Some methods comprise determining whether a characteristic current oscillation or a terminal current exceeding a peak current threshold is present at an overhead line side terminal, and in response, determining that the fault is located in the overhead line section. The methods can be communication-less, wherein the actions are based on local measurements and / or are performed locally to where the fault is located or detected.

The invention discloses a trench gate charge storage-type IGBT and a manufacturing method thereof, which belong to the technical field of power semiconductor devices. Through reasonably introducing asplit trench gate structure and an air floating P-type region, in a condition of not influencing the threshold voltage of the IGBT and conduction, Miller capacitance is reduced, and bad influences brought by Miller effects are improved; the overall gate capacitance is reduced, the device switching speed is improved, the switching losses of the device are reduced, and the compromise between forwardconduction voltage drop and turn-off losses of the traditional CSTBT structure is improved; current and voltage oscillations and EMI problems in the device dynamic starting process are avoided, and the device reliability is improved; electric field concentration effects at the bottom part of the trench are improved, and the breakdown voltage of the device is improved; carrier enhancement effectsat an emitter end of the device are improved, the carrier concentration distribution in a drift region is improved, and the compromise between forward condition voltage drop and turn-off losses is further improved; and besides, the manufacturing method disclosed in the invention has the advantages of low realization difficulty, high product rate and low cost.

Provided are a differential voltage-controlled oscillator (VCO) and a quadrature VCO using center-tapped cross-coupling of a transformer. The differential VCO and the quadrature VCO can be driven by low power through a current reuse structure and have an excellent phase noise characteristic by center-tapped cross-coupling through a transformer. Further, variable capacitance units for frequency variation are divided into variable capacitance units for coarse tuning and variable capacitance units for fine tuning. Therefore, it is possible to obtain a wide tuning range while voltage oscillation gain is reduced. Further, the differential VCO and the quadrature VCO are configured in such a manner that the respective variable capacitance units operate linearly throughout the entire capacitance region due to control voltage distribution by resistors. Accordingly, it is possible to obtain a linear control voltage-oscillation frequency characteristic. The quadrature VCO according to the present invention can output four-phase quadrature signals while having an excellent phase noise characteristic, without substrate loss and current consumption caused by the switching transistors.

This DC converter belongs to one kind of energy converter. It consists of the DC power supply (Vin), the voltage-divided capacitance circuit, the 3-level inversion bridge arm, the resonance inductance, the isolation transformer and the rectifier / filter circuit. Its character lays on that: there is an auxiliary winding (n3) in the isolation transformer beside the primary and the secondary windings (n1, n2). One end of n3 is connected to n1 and two clamp diodes from the joint point to form a clamping circuit. Another end of n3 is connected to the resonance inductance. This converter can eliminate the voltage oscillation induced by the reverse restoration of the rectifier. It decrease the voltage stress across the rectifier and reduces rapidly and effectively the currents through the clamping diodes. All these raise the conversion efficiency and improve the work condition of clamping diodes during light load.

Disclosed is a control system of an LLC converter synchronous rectifier tube. The control system comprises a voltage sampling circuit, a high-pass filter circuit, a PI compensation and effective valuedetection circuit and a control circuit which takes a microcontroller MCU as a core. A principle of circuit waveform oscillation caused by unavoidable parasitic inductance and parasitic capacitance in the circuit is utilized, and when an LLC converter works at high frequency, a drain source voltage VDS (SR) of the synchronous rectifying tube sends a change signal of the drain source voltage in aswitch-off period into the high-pass filter circuit and the PI compensation and effective value detection circuit through the sampling circuit to obtain an effective value amplifying signal of a drainsource voltage oscillation signal caused by parasitic parameters; and the control circuit which takes the microcontroller MCU as the core is adopted to compare the relation between a current value and a collected value in the last time, so that the conduction time of the synchronous rectification tube in the next cycle is changed, the synchronous rectifier tube can be switched off at the optimalswitch-off point, and the optimal efficiency operation of the synchronous rectifier tube can be realized.

A system for monitoring a brain wave response of a fetus in utero, comprises removably connecting an auditory transducer, including at least one biosensor electrode, producing pulsed auditory sounds to a mother's abdomen to detect brain wave activity in a fetus. The transducer is pulsed with one of rectangular waves and tone pips of a selected frequency to emit pulsed audible sounds at predetermined times. The at least one biosensor electrode, including connected amplifier, detects brain stem auditory responses (BAER) of the fetus. For each pulsed audible sound a series of voltage oscillations corresponding to BAER of the fetus are time-locked to the corresponding audible sound. BAER analog output is converted to BAER digital data. A computer-based QEEG (Quantitative EEG) system improves a signal to noise ratio of the BAER digital data using an adaptive optimum filtering algorithm and analyzes the BAER digital data relative to a reference database.

This DC converter belongs to the energy converter and consists of the DC power supply (Vin), two inverter bridge arms, the resonance inductance, the isolation transformer and the rectifier / filter circuit. Its character lays on that; there is an auxiliary winding (n3) in the isolation transformer beside the primary and the secondary windings (n1, n2). One end of n3 is connected to n1 and to two clamp diodes from the joint point to form a clamping circuit. Another end of n3 is connected to the resonance inductance. This converter realizes the zero voltage switching on the rectifier. This can eliminate the voltage oscillation induced by the reverse restoration of the output rectifier. It decrease the voltage stress across the output rectifier and reduces rapidly and effectively the currents through the clamping diodes. All these raise the conversion efficiency and improve the work condition of clamping diodes during light load.

The present invention provides a doubly-fed wind farm sub-synchronous oscillation SVG suppressing method and a device. The method comprises the following steps: acquiring voltage signal(s), current signal(s) and wind farm parameters of the output end(s) of a doubly-fed wind farm, wherein the wind farm parameters comprises a wind speed and a power-transmission line series compensation degree; determining active power signal(s), voltage oscillation amplitude(s) and current oscillation amplitude(s) according to the voltage signal(s) and the current signal(s); determining the working mode of a SVGcontroller; determining module parameter(s) of the SVG controller according to the determined working mode, the voltage oscillation amplitude(s), the current oscillation amplitude(s), oscillation frequencies, the wind farm parameters and a pre-established SVG parameter table, wherein the SVG parameter table is a pre-established corresponding table of the SVG function module parameter(s) and system operation information under different working modes; and performing sub-synchronous oscillation SVG suppressing on the wind farm by using the SVG controller with the determined parameter(s). According to the method, sub-synchronous frequency band signal(s) are filtered from sampling signal(s), and the doubly-fed wind farm is subjected to sub-synchronous oscillation SVG suppressing by using the voltage(s) and the active power(s).

The invention discloses a method for extracting stray parameters of a laminated bus bar based on frequency characteristics of a SiC MOSFET. The method comprises the following steps of firstly settingup a SiC MOSFET double-pulse test platform, and externally connecting the section under test of the laminated bus bar to the test platform; connecting multiple sets of additional capacitors in parallel at both ends of the SiC MOSFET, using the frequency information of oscillation in the off-voltage waveform of the SiC MOSFET before and after the additional capacitors are connected in parallel to obtain the resonance angular frequencies of multiple sets of equivalent circuit models, and further calculating the stray inductance and parasitic capacitance of the laminated bus bar to achieve the extraction of stray parameters of the laminated bus bar. The invention utilizes the high switching speed characteristics of the SiC MOSFET to excite obvious off-voltage oscillations. Compared with the traditional indirect measurement method, the measurement deviation caused by human factors is reduced. In addition, the invention can measure the stray inductance and parasitic capacitance in any section of the laminated bus bar, and the measurement is more flexible and comprehensive.

The invention relates to a method of operating a spin-transfer torque structure to generate voltage oscillations, said structure comprising a first layer of magnetic material having a fixed magnetization vector, a spacer of non magnetic material and a second layer of magnetic material having a free magnetization vector. The method includes the application of a current (jop) through said structure and a magnetic field (Hext) in the plane of the second layer. It makes use of a region of bistability and hysteretic behaviour to trigger and stop the voltage oscillations.

The invention relates to an implementation method of a 3D (three-dimensional) metal printing system, in particular to a 3D metal printing method, which belongs to the technical field of 3D metal printing. In combination with a current or voltage oscillation (or resonance) circuit, the 3D metal printing method adopts a printing method like a ball pen discharging ink and a rolling bearing rolling on a surface to leave an ink print to implement the fast melting of metal powder and fine printing; because a printing head of the 3D metal printing method is a high-temperature part, which still can keep constant high temperature on a printed object like an iron, the problem that metal does not completely melt does not exist, and because of the distance of heat transfer, the printing head also naturally cannot melt the printed object surface, thus truly realizing 3D printing like painting and iron soldering on the printed object surface. Consequently, the method does not have the problem that melted liquid metal is cooled into a drop-like solid once the melted liquid metal gets out of the printing head, as well as the problem of powdery pits which is caused by the incomplete sintering of part of the printed object in the process of laser sintering formation.

The invention discloses a grid-connected converter series virtual impedance method for virtual inertia control. The method comprises the steps that a direct current micro-grid system is established; signal measurement and processing are carried out; small signal analysis is carried out on a reference current equation; small signal analysis is carried out on a grid-connected converter mathematicalmodel and a current inner loop control model; small signal analysis is carried out a power equation; output impedance Zo(s) is calculated; a spike function is extracted and multiplied with a low-passfilter to form a compensation amount; series virtual impedance is applied to a current reference value; PI control and feedforward decoupling control are carried out; alpha beta transform and SVPWM modulation are carried out. According to the invention, the method has the advantages of simple structure and high efficiency; when the direct current micro-grid system is unstable, the control goals ofincreasing system damping, suppressing direct current voltage oscillation, and ensuring voltage quality during steady-state operation are realized.

A system for the production of localized audible sound, including a source of voltage oscillations in the ultrasonic frequency range, at a reference frequency. The voltage source is connected to a first ultrasonic transducer, emitting a first beam of ultrasonic waves (the reference beam) in a relatively narrow beam, in a desired direction. The same voltage source is connected to a phase shifter, feeding a second ultrasonic transducer from which an ultrasonic wave is emitted, of the same frequency and intensity as the reference beam, but phase shifted relative to it.

Provided is a voltage-controlled oscillator with a wide oscillation frequency range and linear characteristics, which can linearly change an oscillation frequency versus control voltage due to a variable capacitance range increased by several MOS transistors additionally connected to an LC resonant circuit, and can control the oscillation frequency range by adjusting numbers, widths, lengths and operation regions of the MOS transistors. Thus, the voltage-controlled oscillator with a wide oscillation frequency range and linear control voltage-oscillation frequency characteristics without using a switching device can be implemented.

The invention discloses a three-level full-bridge DC conversion device. A low-voltage diode can be directly adopted by a secondary rectifier side of a transformer of the three-level full-bridge DC conversion device to achieve high voltage output, and meanwhile, the problem of non-uniform voltage, caused by the reverse recovery inconsistency, of the diode which is directly connected in series is solved. In most of the switching period, a secondary rectifier diode is clamped by a secondary flying capacitor, so that voltage oscillation and spikes on the diode can be eliminated without adding an auxiliary circuit and reduction of the volume and improvement of the conversion efficiency are facilitated. Output voltage of a secondary rectifier bridge has certain DC bias, the secondary rectifier bridge can output higher voltage than a conventional rectifier circuit, and current ripples on an output filter inductor are smaller, so that improvement of the DC voltage utilization ratio and the power density of the device is facilitated and the volume and the weight of the device are reduced.

The invention relates to a stable control method for inhibiting voltage oscillation of a flexible DC power transmission system. The method is characterized by comprising that an axis-d control channeland / or an axis-q control channel are / is provided with an AC voltage stabilizer in the outer ring of a flexible DC converter station control system in the flexible DC power transmission system; a gaincoefficient and an output amplitude limit value of the AC voltage stabilizer are determined; an output current compensation value of the AC voltage stabilizer after that the gain coefficient and output amplitude limit value are determined is obtained, and added to an original reference current in the outer ring of the flexible DC converter station control system to obtain a reference current in the outer ring of the flexible DC converter station control system; and the reference current is output to the inner ring of the flexible DC converter station control system, and voltage oscillation ofthe flexible DC power transmission system is inhibited. The method can be widely applied to the field of flexible DC power transmission.

The invention provides a double-fed wind power plant sub-synchronous oscillation SVC suppression method and device. The method comprises the following steps: acquiring a voltage signal, a current signal and wind power plant parameters of the double-fed wind power plant output end, wherein the wind power plant parameters comprise wind speed and power transmission line series compensation; ;determining an active power signal, a voltage oscillation amplitude and a current oscillation amplitude according to the voltage signal and the current signal; determining a work mode of a SVC controller; determining module parameters of the SVC controller according to the determined work mode, the voltage oscillation amplitude, the current oscillation amplitude, the oscillation frequency, the wind powerfield parameter and a pre-established SVC parameter table, wherein the SVC parameter table is the pre-established SVC function module parameter and system operation information corresponding table under different work modes; and performing sub-synchronous oscillation SVC suppression on the wind power field by using the SVC controller with determined parameter. The sub-synchronous band signal is filtered from a sampling signal, and the sub-synchronous oscillation SVC suppression is performed on the double-fed wind power plant by using the voltage and the active power.

The invention discloses a reverse blocking type IGBT and a manufacturing method therefor, and belongs to the technical field of a semiconductor power device. By introducing trench emitter and trench collector structures, the reverse breakdown voltage of a device is improved without influencing the threshold voltage and switch-on of an IGBT device; the overall gate capacitance is lowered, the switching speed of the device is improved, the switching loss and driving power consumption of the device are lowered, and the compromising relation between forward switch-on voltage drop and switch-off loss of the conventional CSTBT structure is improved; the problems of current, voltage oscillation and EMI in the device starting dynamic process can be avoided, and device reliability is improved; theelectric field concentration effect at the bottom of the trench is improved, the forward breakdown voltage of the device is improved, and reliability of the device is further improved; and the currentcarrier enhancement effect at the emitter end of the device is further improved, the current carrier concentration distribution in a drift region can be improved, and compromising between forward switch-on voltage drop and switch-off loss can be further improved. The manufacturing method disclosed in the invention is compatible with the existing manufacturing process of a CSTBT device.