72results about How to "Changing impedance" patented technology

An apparatus for breaking a line bidirectional current and a control method therefor. The apparatus comprises a breaking current branch circuit (9) and an on-state current branch circuit (30), wherein the breaking current branch circuit (9) comprises one nonlinear resistor (13) being connected in parallel to one first power semiconductor device (5), or one nonlinear resistor (13) being connected in parallel to at least two first power semiconductor devices (5) mutually connected in series; and the on-state current branch circuit (30) comprises at least one bidirectional power semiconductor switch (12) being connected in series to at least one high-speed isolation switch (11). The apparatus also comprises a bridge-type branch circuit, wherein the bridge-type branch circuit comprises two bridge arms constituted by four identical current commutation branch circuits. The apparatus can break a bidirectional current.

A fuel cell system includes: a fuel cell having laminated cells; a measuring unit that measures an impedance of the cell and a purging unit that performs purging to discharge residual water from a gas passage. The cell includes a wet region and a dry region which are set depending on a distribution of water in the cell when the purging is executed so as to set a total amount of water in the fuel cell to be a necessary amount of water to start up the fuel cell; the measuring unit measures the impedance at a local portion located at a boundary portion between the wet region and the dry region in the cell; and the purging unit terminates the purging when the impedance measured by the measuring means is larger than a predetermined reference threshold value.

The invention discloses a plate or bridge structure of a local resonance acoustic black hole (ABH). The local resonance acoustic black hole structure comprises an acoustic black hole region (a region which is gradually thinned), a local vibrator (such as a mass spring unit) and an acoustic black hole extension part. According to the local resonance acoustic black hole structure disclosed by the invention, the local vibrator is constituted by units having the properties of a spring vibrator, so that an effective action frequency range of an acoustic black hole effect is reduced, and subsequently, a vibration control effect of the acoustic black hole structure is effectively improved. The local resonance acoustic black hole structure disclosed by the invention has a broad application prospect in vibration absorption and noise reduction of structures.

A multi-resonant antenna device having good VSWR characteristics even in the UWB band, and a wireless communication apparatus including the antenna device are provided. The antenna device includes a substrate, an antenna main body surface-mounted at a corner of the substrate, and slits. The antenna device resonates at two different resonance frequencies. The slits are arranged to bring a VSWR value at a frequency between the two resonance frequencies closer to VSWR values at the two resonance frequencies. The slits include capacitive adjustment slit portions and inductive adjustment slit portions. The slits are provided in an area where the density of a current flowing on ground conductor surfaces is highest. The slits are arranged perpendicularly or substantially perpendicularly to a direction of this current. Specifically, the slits are provided near and parallel or substantially parallel to an open end of the radiating electrode portion. The lengths of the slits are set to one-eighth of a wavelength at a frequency corresponding to the highest VSWR value in the range between the two resonance frequencies.

A compact position sensor with high operational reliability is provided. This sensor has a tubular detection coil, a magnetic core movable in the detection coil, a drive circuit for the detection coil, a signal processing circuit for converting a change in impedance of the detection coil into an electric signal, and a guide means for guiding a movement of the magnetic core in the detection coil. The guide means has a guide portion connected to the magnetic core and a support portion for slidably supporting the guide portion. The magnetic core can be smoothly displaced in the detection coil without contacting an inner surface of the detection coil by a sliding movement of the guide portion relative to the support portion.

The invention relates to a traction power supply network tail end voltage boosting device with a power fusing function and a method of the device. The device includes a multiple voltage reduction module and a power-fusing current-converting module; the multiple voltage reduction module is connected into two power supply arm power sources of the tail end of a traction power supply network and includes two single-phase multi-winding transformers of the same structure which are correspondingly connected into the two power supply arm power sources respectively through connection switches; the power-fusing current-converting module is used for performing energy conversion on the two power supply arm power sources and includes a plurality of current conversion sub modules; one set of voltage is connected into two input sides of each current conversion sub module through corresponding secondary windings of the two single-phase multi-winding transformers, so that energy conversion can be performed; and through controlling the switch-on of the current conversion sub modules, output voltage can be boosted, and power fusion of the two power supply arms can be performed. According to the method of the invention, the voltage of the tail end of the traction power supply network can be stabilized and boosted through controlling the power-fusing current-converting module. The device and the method of the invention have the advantages of simple structure, low cost, power fusion and train power network resonance suppression, and can boost the voltage of the tail end of the traction power supply network.

The invention discloses a radio frequency matching network, comprising a radio frequency output port and at least two radio frequency input ports. A matching circuit between the radio frequency input ports and the radio frequency output port comprises a matching circuit which a first constant inductance and a first constant capacitor are connected in series to form. One end of the matching circuit is provided with a second grounded constant capacitor. The radio frequency matching network further comprises a first branch circuit. The first branch circuit comprises a first constant additional capacitor and a first switch which are connected with each other in series, and is connected with any of the first constant capacitor and the second constant capacitor in parallel. The invention also discloses plasma treatment equipment comprising the radio frequency matching network. Due to each element is all a constant element, the radio frequency matching network has small volume, low cost and faster matching speed, and at the same time, the impedance of the radio frequency matching network can be prominently changed by the first switch, and when the load impedance is greatly changed, the plasma treatment equipment still can favorably realize impedance matching.

The invention belongs to an MEMS ultrasonic transducer technology, in particular to an MEMS piezoelectric ultrasonic transducer with a sound tube. The MEMS piezoelectric ultrasonic transducer comprises an MEMS piezoelectric ultrasonic transducer body and at least one sound tube, wherein the interior of the sound tube is a silicon substrate of a cavity structure, wherein each sound tube comprises at least three sound wave conduits, and the first sound wave conduit and the third sound wave conduit formed by etching and bottom polishing after piezoelectric lamination is deposited on the CSOI wafer are bonded with the second sound wave conduit formed by etching on the Si wafer. The sound tube can conduct sound waves generated by the back of the MEMS piezoelectric ultrasonic transducer to the top of the MEMS piezoelectric ultrasonic transducer, and due to the sound amplification effect of the sound tube, the sound waves transmitted from the sound tube are enhanced. Meanwhile, sound waves generated by the back of the MEMS piezoelectric ultrasonic transducer transmitted by the sound tube and sound waves generated by the top of the MEMS piezoelectric ultrasonic transducer can be superposedand transmitted, so that the intensity of the sound waves generated by the ultrasonic transducer is further enhanced. According to the transducer, the intensity of sound waves generated by the MEMS ultrasonic transducer can be enhanced, and the energy conversion efficiency of the MEMS piezoelectric ultrasonic transducer is improved.

A circuit for tuning an impedance matching network is disclosed. The circuit includes a current sensor, a control circuit coupled to the current sensor and a reference current source and a tunable capacitor coupled to the control circuit. The control circuit is configured to generate a control signal based on an output of the current sensor, wherein the control signal is configured to vary a capacitance of the tunable capacitor.

The invention discloses a method for inhibiting an overvoltage and an overcurrent of a resonant transformation circuit and the resonant transformation circuit. The resonant transformation circuit comprises an inverter bridge, a transformer, a resonant capacitor, a resonant inductor and a resonant branch circuit connected in parallel with the resonant capacitor. The resonant capacitor, the resonant inductor and a transformer primary winding are connected in series. A series circuit of the resonant capacitor, the resonant inductor and the transformer primary winding is connected with an output end of the inverter bridge. The resonant branch circuit comprises an auxiliary resonant capacitor and a pressure-sensitive device. The auxiliary resonant capacitor is connected in series with the pressure-sensitive device. By dynamically changing parameters of the resonant circuit, a voltage stress and a current stress of the resonant circuit under the abnormal working condition can be effectively reduced and the working reliability of the circuit is improved.

The invention relates to a printed circuit board and a method for controlling the impedance of a through hole structure on the same. In the method, an equivalent dielectric constant between through hole structures or between the through hole structure and a reference structure is changed by a nonmetal hole or a nonmetal groove formed on a dielectric between at least two through hole structures or between the through hole structure and the reference structure, the impedance of the through hole structure is further changed, and negative influence caused by increasing a distance between the through hole structure and the reference structure in the prior art on the wiring of other lines of the circuit board is avoided. Therefore, the purpose that the impedance of the through hole structure in the high-density and high-power printed circuit board can be controlled and is free from the technological level can be achieved.

This invention relates to an impedance-transfer amplifier with a negative impedance compensation function including elements of single-stage impedance-transfer amplifier and a negative impedance compensator connected to the output end of the amplifier element, which is realized in many ways including a negative resistance element composed of positive and negative circuits and a compensation circuit against the parasitic capacitance effect generated by its output end, and the compensator increases the equivalent earth impedance of the output of the single-stage impedance-transfer amplifier and compensates the parasitic capacitance effect.

The difference in voltages measured upstream and downstream of a pressure junction in a power distribution system produced by the energizing power is divided by the measured current to calculate a value that is a function of the impedance of the pressure junction, which is monitored for deterioration. To eliminate noise resulting from dividing a small number by a large number and transients in the power distribution system, the impedance is calculated from the squares of the voltage differences and currents for a large number of samples, and the change between successive calculations is limited to produce a stable median value.

The invention discloses a resonant mode wireless electric energy transmission system capable of self-tuning impedance. The system comprises an emitting end rectifier, an inverter and an emitting end resonance loop; the innovation is that a resonance control unit is arranged in the resonant mode wireless electric energy transmission system; a first terminal is connected with a current sampling portof the resonance control unit through a current sampling circuit; the first terminal and a second terminal are connected with a voltage sampling port through a voltage sampling circuit; an equivalentcapacitance regulating circuit is connected to the resonance loop. The transmission system disclosed by the invention has the advantages that the resonant wireless electric energy transmission systemcapable of self-tuning impedance and the control method are provided, the method is simple and easy to do, and the charging effect of the resonant wireless electric energy transmission system can beeffectively improved.

The invention discloses an apparatus and a method used for detecting internal and external crack defects of a metal material. The apparatus comprises an input unit, a detection coil, a signal extraction unit, and a signal processing unit. The input unit comprises at least two signal genitors used for respectively generating excitation signals with different frequencies, an addition circuit, and a power amplifying circuit connected with the addition circuit. The detection coil is connected with the power amplifying circuit, and is used for induce a workpiece requiring detection, such that frequencies are changed high and low. The signal extraction unit has a pre-amplification circuit connected with the detection coil, at least two band-pass filters which are connected with the pre-amplification circuit, and multi-way switches connected with the band-pass filters, wherein the number of the band-pass filters matches the number of the signal generators. The signal processing unit is connected with the multi-way switches, and is used for evaluating the quality of the workpiece requiring detection according to detection signals sent by the multi-way switches. With the apparatus provided by the invention, more information about the size and shape of the defects can be obtained, such that defect evaluation upon metal materials can be improved, and detection information can be more complete.

The invention provides a base. The base comprises a metal circular disk with a lug boss, and insulating rings, wherein the insulating rings are nested on the outer sides of the lug boss; a concave part is arranged on the bearing surface of the metal circular disk; the depth of the concave part is variable in the radial direction of the metal circular disk. By adoption of the base, the uniformity of the processing technology can be improved; and furthermore, the base is low in cost and long in service life. In addition, the invention also provides plasma processing equipment.

A thin film balun of the present invention comprises: an unbalanced transmission line UL including a first line portion L1 and a second line portion L2; a balanced transmission line BL including a third line portion L3 and a fourth line portion L4 that are positioned facing the first line portion L1 and the second line portion L2 and electromagnetically coupled to the first line portion L1 and the second line portion L2, respectively; an unbalanced terminal UT connected to an end of the first line portion L1; a first balanced terminal BT1 connected to the third line portion L3; a second balanced terminal BT2 connected to the fourth line portion L4; and a ground terminal G connected to the third line portion L3 and the fourth line portion L4, wherein the ground terminal G has an extension that extends from the ground terminal G to an area at the unbalanced terminal UT side.

The invention relates to a multipurpose tag antenna. The multipurpose tag antenna comprises a radiation patch, a dielectric substrate and a metal grounding plate. The radiation patch is a metal patch, and is printed on the front face of the dielectric substrate, and annularly-intersected micro-strip patches are arranged on the surfaces of the radiation patch; a symmetrical and annular-intersected dipole antenna structure is formed by the micro-strip patches, and the resonant frequency, the input impedance and the operation bandwidth of the antenna are adjusted by adjusting the number of circular rings, the size of the radius and the filling degree of the circular rings; a RFID chip is arranged in the center of the radiation patch, and the radiation patch is connected with the chip through a micro-strip feed line; the metal grounding plate is printed on the back face of the dielectric substrate; a high-dielectric-constant dielectric plate is also pasted on the back face of the grounding plate. The multipurpose tag antenna is simple and reasonable in structural design, low in cost and suitable for multiple complex environments; the radiation patch adopts the micro-strip patches formed in the mode that the multiple metal circular rings are intersected, variation of tag resonance frequency points can be achieved, and therefore the antenna miniaturization aim can be achieved.

The invention belongs to the technical field of strong magnetic fields, and discloses a flat-top magnetic field generating device and method. The device comprises a normal-temperature magnet, a charger, a trigger circuit, a capacitor branch, a current sensor, an adjusting branch, a driving protection circuit and a controller.The capacitor branch is used for supplying power to the normal-temperature magnet; the adjusting branch is used for being equivalent to a variable resistor in adischarging process and controlling acurrent by changing acircuit impedance; and the controller is used for calculating a charging voltage of the capacitor before discharging is started, making the charger charge the capacitor, and making switch triggering of the capacitor branch according to a pre-calculated time sequence in adischarging stage. Due to afact that the normal-temperature magnet is used, compared with a superconducting magnet and low-temperature magnet low-temperature pulse magnet scheme, construction cost and maintenance cost are low; and due to the fact that negative feedback control is formed by the current sensor, anadjusting branch, the controller, adriving circuit and the like, waveform repeatability is good, and accuracy is high.

The invention discloses an impedance matching adjusting method and device applied to a radio frequency power supply, and the method comprises the steps: collecting incident and reflected waves between an impedance matching network and a load, determining whether the impedance is matched or not according to the amplitude and phase angle of the incident wave and the reflected wave, and if not, obtaining an amplitude difference voltage and a phase angle difference voltage; acquiring a control signal according to the amplitude difference voltage and the phase angle difference voltage, and inputting the control signal to a controlled current source to obtain a control current; increasing the magnetic induction intensity of a magnetic core by the control current, so as to increase the saturation degree of the magnetic core and influence the effective magnetic conductivity of the magnetic core is influenced, so that the inductance value of an inductor wound around the magnetic core in the impedance matching network is changed, and the impedance of the impedance matching network is further changed. The technical problems that in the prior art, a servo stepping motor is used or the number of parallel capacitors is controlled to change the capacitance value in a matching box to achieve impedance matching, cost is high, the adjustable range is small, the adjusting process is not smooth enough, and the design requirement for the capacitance value is high are solved.

The invention provides a tilt angle sensor and belongs to the technical field of sensors. The tilt angle sensor comprises an electrode and a shell with a cavity structure, wherein an electrolyte is injected into the cavity; an electrode hole running through the shell is formed in the shell; an electrode is inserted into the electrode hole; one end of the electrode is inserted deep into the cavity while the other end of the electrode is located in the shell; a ceramic material is taken as the material of the shell. According to the invention, the shell is made from the ceramic material, the strength of the shell made from the ceramic material is higher, pressing injection molding can be applied and the design and processing of the tilt angle sensor are more convenient. Besides, the surface property and the processing property of the shell made from the ceramic material are greatly better than those of the shell made from glass material, so that the tilt angle sensor with more excellent performance, higher reliability, diverse structure and wider application scope can be manufactured.

The invention provides a serial-parallel mixed type filtering and protecting device of passive power. The serial-parallel mixed type filtering and protecting device of the passive power does not easily resonate with a system, effectively reduces total current of a system, and has an obvious energy-saving effect. The serial-parallel mixed type filtering and protecting device of the passive power comprises a first electric reactor (L1), a first capacitor (C1), a transformer (T1), a first sing-phase silicon controlled rectifier (Q1), a second single-phase silicon controlled rectifier (Q2), a first voltage dependent resistor (Y1), a second voltage dependent resistor (Y2), a current limiting reactor (L0), a lightning arrester (B1), a second electric reactor (L2), a second capacitor (C2), a third electric reactor (L3), a third capacitor (C3) and a vacuum contactor (K). According to the serial-parallel mixed type filtering and protecting device of the passive power, the serial-parallel mixed mode is adopted, the electric reactors and the capacitors are connected in series to be designed with traditional filtering branches in a mixed mode, the capacity requirement of series branches is effectively reduced, the filtering performance is improved, and meanwhile the cost is reduced. The package scheme is based on passive power elements, a protecting circuit is also based on self triggering, the reliability is high and the service life is long.