51 results about "Shunt impedance" patented technology

An EIT system includes a plurality of voltage sources for supplying a corresponding plurality of voltages to a corresponding number of other structures, voltage source calibration means for calibrating each voltage source, and switching means for individually connecting the calibration means to each voltage source in succession during a period when each other structure is in an inactive condition. Calibrating respective voltages and currents for each voltage source compensates for shunt impedance of each voltage source. A method for calibrating the system includes individually connecting the calibration means to each voltage source in succession during a period when each other structure is in an inactive condition for calibrating all of said voltage sources in the same way.

The modem of a portable computer device draws a portion of its required power from the telephone line using a low noise switching power supply. The switching power supply can alternatively or additionally assist in keeping the battery of the portable computer device charged. The generation or propagation of electrical noise on the input telephone line is minimized by actively maintaining a constant input impedance from the telephone line to the modem. In one embodiment, a switchable shunt impedance is placed in parallel with the input to a PWM switching power supply and actively controlled to maintain the impedance of the input of the PWM switching power supply constant to the extent that a constant current draw is maintained. Thus, the net input impedance of the modem as sensed by the telephone line is stable and balanced despite the chopping of the current on the telephone line due to the switching of the PWM switching power supply, thus minimizing or eliminating the generation of electrical noise back to the telephone line. In another embodiment, a constant current regulator is placed in series with a PWM switching power supply to maintain a constant input impedance to the modem as sensed by the telephone line.

A wide band antenna. The antenna comprises a radiating element in a corner region of a substrate, spaced apart from a ground plane occupying a substantial portion of a remaining area of the substrate. Series and shunt impedance matching elements are connected to the radiating element to control the antenna operating parameters. The radiating element is connected to a signal feed.

A device which improves the electrical and thermomechanical performance of an RF cavity, for example, in a disk-loaded accelerating structure. A washer made of polycrystalline diamond is brazed in the middle to a copper disk washer and at the outer edge to the plane wave transformer tank wall, thus dissipating heat from the copper disk to the outer tank wall while at the same time providing strong mechanical support to the metal disk. The washer structure eliminates the longitudinal connecting rods and cooling channels used in the currently available cavities, and as a result minimizes problems such as shunt impedance degradation and field distortion in the plane wave transformer, and mechanical deflection and uneven cooling of the disk assembly.

A differential variable gain amplifier (1) comprises eight identical variable gain stages (8a to 8d) which are arranged in two groups, namely, a high gain group (19) and a low gain group (20). The first gain stage (8a) is coupled directly to a pair of positive and negative main input terminals (4,5) for receiving a differential input signal to be amplified. A pair of voltage divider impedance chains (14) comprising identical capacitors (C1a to C1g) define taps (17b to 17h) through which the input signal is applied to the corresponding gain stages (8b to 8h) in progressive steps of attenuation. Each gain stage (8) comprises a pair of identical variable gain amplifier elements (11) which amplify the respective positive and negative ends of the differential input signal. Only one of the gain stages (8a to 8h) is selected at any one time by a control circuit 10. The outputs from the gain stages (8) of the high gain group (19) are applied to positive and negative high gain output terminals (28,29). The output of the gain stages (8) of the low gain group (20) are applied on positive and negative low gain output terminals (33,34). A pair of selectively activatable shunt-shunt feedback circuits (42a,42b) each comprising a variable gain feedback amplifier (43a,43b) provide variable shunt impedance at the main input terminals (4,5) for maintaining the input impedance of the variable gain amplifier (1) within a predetermined input impedance range as the gain of the variable gain amplifier (1) is varied, and when the variable gain amplifier (1) is operating at the high end of its gain range. A passive shunt impedance circuit (40) comprising a plurality of resistive shunt impedance elements are independently selectively shuntable across the main input terminals (4,5) for maintaining the input impedance of the variable gain amplifier (1) within the predetermined input impedance range when the variable gain amplifier (1) is operating at the low gain end of its gain range.

The invention provides an apparatus for shunting leakage current of a solid state switching device (SSSD) (10). The apparatus selectively provides a shunt pathway to divert current away from the output load based on the switching state of the SSSD. The apparatus may include a shunt impedance component (14) connected to the SSSD, and a switching element (16) for selectively connecting the other end of the shunt impedance component to ground based on the switching state of the SSSD. Accordingly, when the SSSD is turned off, the switching element is switched to a state that connects the shunt impedance component to ground, thereby shunting leakage current.

The invention provides a position detection device and method thereof. A position detection device comprises a plurality of intersecting regions which consist of a plurality of conductive strips to form a plurality of intersecting regions, wherein a depressed intersecting region is formed when depressed conductive strips electrically contact with each other. The contact position and the total impedance can be determined based on the depressed intersecting region, wherein the total impedance is the shunt impedance of all the depressed intersecting regions.

Disclosed is a diagnostic resonant cavity for determining characteristics of a charged particle beam, such as an electron beam, produced in a charged particle accelerator. The cavity is based on resonant quadrupole-mode and higher order cavities. Enhanced shunt impedance in such cavities is obtained by the incorporation of a set of four or more electrically conductive rods extending inwardly from either one or both of the end walls of the cavity, so as to form capacitive gaps near the outer radius of the beam tube. For typical diagnostic cavity applications, a five-fold increase in shunt impedance can be obtained. In alternative embodiments the cavity may include either four or more opposing pairs of rods which extend coaxially toward one another from the opposite end walls of the cavity and are spaced from one another to form capacitative gaps; or the cavity may include a single set of individual rods that extend from one end wall to a point adjacent the opposing end wall.

A single trigger/shunt coil is utilized for combined induced magnetic field triggering and shunt impedance. The single coil connected in parallel with the high temperature superconducting element, is designed to generate a circulating current in the parallel circuit during normal operation to aid triggering the high temperature superconducting element to quench in the event of a fault. The circulating current is generated by an induced voltage in the coil, when the system current flows through the high temperature superconducting element.

A feeder power source for a network power system includes a network transformer having a delta three-phase primary winding and a three-phase secondary winding; a three-phase primary feeder electrically connected to the delta three-phase primary winding; a three-phase secondary bus electrically connected to the three-phase secondary winding; and a three-phase electrical switching apparatus structured to open and close the three-phase primary feeder. A network protector includes a network relay and a three-phase circuit breaker structured to open and close the three-phase secondary bus. A first circuit is electrically connected between at least one phase of the three-phase primary feeder and ground, and is structured to unbalance shunt impedance to the three-phase primary feeder ground. A second circuit detects a shift in system neutral and detects that the three-phase primary feeder is opened by the three-phase electrical switching apparatus.

The invention provides an interdigital longitudinal magnetic mode drift tube linear accelerator of a separation focusing type, and belongs to the technical field of linear accelerators. The characteristic of small size of a permanent magnet quadrupole iron is utilized, and a focusing magnet is placed in a single drift tube, so that the shunt impedance and the average acceleration gradient of the acceleration tube can be effectively improved. According to the first drift tube linear accelerator, a plurality of drift tubes are arranged in a transverse focusing section C at intervals, and a permanent-magnet quadrupole magnet is arranged in each drift tube in the axial direction. A drift tube linear accelerator of the other type provided by the invention is an improvement on a first drift tubelinear accelerator, and the synchronous phase of a drift tube gap in a transverse focusing section C is controlled, so that a 0-degree accelerating section B is formed after the transverse focusing section C, thereby saving the length of a longitudinal bunching section A and further improving the accelerating efficiency.

The invention provides a two-photon medical moderate-energy stationary wave accelerating tube. The two-photon medical moderate-energy stationary wave accelerating tube comprises a cavity chain body, an electron gun sealing at the two ends of the cavity chain body and a deflection device with a titanium window. The side surface of the cavity chain body is fixedly connected with a rectangular waveguide; the rectangular waveguide is fixedly connected with a microwave input window and a sputter ion pump; the cavity chain body is a accelerating cavity chain formed by a accelerating cavity and a coupled cavity, wherein the beam aperture of the accelerating cavity is between 6 mm and 8 mm; and the length of the cavity chain body is between 1.2 m and 1.4 m. According to the invention, the above beam aperture and cavity chain body are combined to use, and the total length of the accelerating tube is less than 1.6 m, so that the accelerating tube has medium length and high shunt impedance. Therefore, the accelerating tube is compatible with output dosage rate and ray quality of a low-energy accelerating tube and a moderate-energy accelerating tube, after the electronic targeting is achieved, any second gear 6-14MeV X-ray radiation can be offered and the output dose rate is not less than 3Gy/min.m, and any third gear 5-14MeV E radiation can be offered and the dose rate is not less than 4Gy/min.m.

The invention provides a method for improving adaptability of distributed photovoltaics to an AC/DC hybrid microgrid. The method includes the steps of determining double closed loop control parametersof a distributed photovoltaic grid-connected system under a strong power grid condition, the double closed loop control parameters including a proportional control factor of a PI controller, an integral control factor of the PI controller and a capacitance current feedback factor; realizing virtual shunt impedance based on output impedance under a weak power grid condition; and determining valueranges of the parameters and shunt inductance of a phase lag link after system compensation. The method provided by the invention ensures that the system can stably run under the strong power grid condition, and at the same time, can satisfy requirements of a stable state and a transient state; and improves adaptability of the system to a weak power grid, i.e., through double closed loop parametersetting under the strong power grid condition, the method provided by the invention ensures grid connection performance under the strong power grid condition, and a method of lag link compensation and shunt inductance after adoption of virtual shunt impedance is employed to improve adaptability of the system to the weak power grid.

The invention discloses a shunt impedance parameter determining method for measuring a transient current, and solves a problem that a conventional miniature impedance determining method cannot accurately measure a shunt impedance parameter because of low measurement precision. The method employs a variable frequency AC current source, a multi-purpose meter, a lock-in amplifier, a reference impedance element, and an RLC analyzer which is used for measuring an impedance angle of the reference impedance element. The reference impedance element should meet requirements that a relative error can be neglected when the RLC analyzer is used for measuring an impedance value and the impedance angle can be obtained accurately. The method provided by the invention provides a solution to a problem that a conventional RLC analyzer or network analyzer cannot precisely determine an impedance parameter of a shunt because the impedance parameter of the shunt is too small. The method can precisely determine the shunt impedance parameters at different frequency points according to a frequency component of the transient current, is good in determining results of the shunt impedance parameters, and is accurate and reliable.

An electrical filter structure includes a first filter core structure and a second filter core structure. The first filter core structure includes a plurality of shunt impedance elements. Similarly, the second filter core structure includes a plurality of shunt impedance elements. Shunt impedance elements of the first filter core structure are arranged in different conducting layers of a multi-layer structure, and shunt impedance elements of the second filter core structure are arranged in different layers of the multi-layer structure. Transmission lines used to implement the shunt impedance elements are interleaved.

The present invention provides a light emitting diode (LED) device. The LED device include a driver, a first LED coupled in series with the driver, and an impedance-providing component coupled in parallel with the first LED and in series with the driver. The impedance-providing component provides a shunt impedance having a value that varies in positive proportion with a variation in an ambient temperature. The driver is respectively coupled in series with the first LED and the at least one impedance-providing component. The driver provides a drive current divided to flow through the first LED and the at least one impedance-providing component according to the shunt impedance and the internal impedance.