814 results about "Shunt capacitance" patented technology

The invention relates to LED replacement lamp suitable for operation with a high frequency fluorescent lamp ballast, comprising—a LED load (LS) comprising a series arrangement of LEDs,—a first lamp end circuit comprising—a first lamp pin (LP1) and a second lamp pin (LP2) for connection to a first lamp connection terminal comprised in the high frequency fluorescent lamp ballast,—a first rectifier (D1-D4; D1,D2) equipped with at least one input terminal coupled to the second lamp pin and with first and second output terminals coupled to respective ends of the LED load, the first rectifier comprising at least two diodes, one of which is shunted by a first capacitor (C1),—a second lamp end circuit comprising—a third lamp pin (LP3) and a fourth lamp pin (LP4) for connection to a second lamp connection terminal comprised in the high frequency fluorescent lamp ballast,—a second rectifier (D5-D8, D5, D6) equipped with at least one input terminal coupled to the fourth lamp pin and with first and second output terminals coupled to respective ends of the LED load, the second rectifier comprising at least two diodes, one of which is shunted by a second capacitor (C2), wherein the first capacitor and the second capacitor form a series arrangement coupled between the second lamp pin and the fourth lamp pin.

A conducting sheath is provided along at least a portion of an implantable medical device lead, and preferably along substantially its entire length, for mitigating heating problems arising during magnetic resonance imaging (MRI) procedures, particularly problems arising due to a problem described herein as the “coiling effect.” During device implant, the clinician may elect to wrap or coil excess proximal portions of leads around or under the medical device being implanted. Thereafter, during MRI procedures, shunt capacitance may develop between the housing of the implantable device and insulated coils within the proximal portions of the lead that are near the device, resulting in greater lead heating during the MRI. The conducting sheath helps suppress induced currents and also reduces or eliminates shunt capacitance. The conducting sheath may be, for example, formed using a metal mesh or a conducting polymer tube incorporating non-ferrous metal powders. The sheath may be formed in ¼ wavelength segments.

Plasma parameters such as plasma ion density, wafer voltage, etch rate and wafer current in the chamber are determined from external measurements on the applied RF bias electrical parameters such as voltage and current. The method includes sensing RF parameters corresponding to an input impedance, an input current and an input voltage at the input of the impedance match element to a transmission line coupled between the bias generator and the wafer pedestal. The method continues by computing a junction admittance of a junction between the transmission line and the electrode within the wafer pedestal from the input impedance, input current and input voltage and from parameters of the transmission line. The method further includes providing shunt electrical quantities of a shunt capacitance between the electrode and a ground plane, and providing load electrical quantities of a load capacitance between the electrode and a wafer on the pedestal. The method further includes computing at least one of the plasma parameters from the junction admittance, the shunt electrical quantities, the load electrical quantities and a frequency of RF bias power applied to the electrode.

An exemplary fast start-up crystal oscillator with reduced start-up time. The exemplary oscillator reduces the start-up time (i.e., the time taken to attain sustained stable oscillations after the power is turned on) by increasing the negative resistance of a circuit. Increasing the negative resistance increases the rate of growth of the oscillations, thereby reducing start-up time. The exemplary crystal oscillator includes a gain stage with negative resistance. A crystal with shunt capacitance is placed in the feedback loop of the gain stage. A buffer is coupled to the gain stage such that it blocks the crystal shunt capacitance from loading the gain stage, effectively increasing the negative resistance of the gain stage. Further, an oscillation detection and control circuit is coupled between the crystal and the gain stage. The oscillation detection and control circuit connects the buffer during start-up, and disconnects the buffer once an oscillation signal attains sustained stable oscillations.

A monolithic capacitor structure includes opposed and overlapping plates within a dielectric body, which are arranged to form a lower frequency, higher value capacitor. Other conductive structure is located either inside the dielectric body or on an external surface thereof and is effective to form a higher frequency, lower value capacitor in parallel with the lower frequency, higher value capacitor. The resulting array of combined series and parallel capacitors integral with the dielectric body provides effective wideband performance in an integrated, cost-effective structure.

A method to locate a fault from one end of a section of a power line utilizing measurements of current, voltage and angles between the phases at a first end of said section. Symmetrical components of currents are calculated for the current and voltage measurement at the first end. A value of impedance is calculated for an extra link between the terminals with the impedance for the positive sequence equal to: $\left({\underset{\_}{Z}}_{1\mathrm{LB}\&\mathrm{AB}}=\frac{{\underset{\_}{Z}}_{1\mathrm{LB}}{\underset{\_}{Z}}_{1\mathrm{AB}}}{{\underset{\_}{Z}}_{1\mathrm{LB}}+{\underset{\_}{Z}}_{1\mathrm{AB}}}\right)\mathrm{where}\text{:}$

• Z_1AB=impedance for the positive sequence of the extra link,
• Z_1LA=positive-sequence impedance of the healthy line. A compensation is determined for the shunt capacitance with the aid of an equation of the form:

B₂^{comp<sub2>—</sub2>1}(d_{comp<sub2>—</sub2>1})²+B₁^{comp<sub2>—</sub2>1}d_{comp<sub2>—</sub2>1}+B₀^{comp<sub2>—</sub2>1}=0 where:

B₀^{comp<sub2>—</sub2>1}=A_{0<sub2>—</sub2>Re}^{comp<sub2>—</sub2>1}A_{00<sub2>—</sub2>Im}^{comp<sub2>—</sub2>1}−A_{0<sub2>—</sub2>Im}^{comp<sub2>—</sub2>1}A_{00<sub2>—</sub2>Re}^{comp<sub2>—</sub2>1}.

The zero-sequence current is determined from the healthy line of a section of parallel power lines. A distance to a fault is calculated for the parallel line section. The distance to the fault from the first end is calculated using a quadratic equation of the form:

B₂d²+B₁d+B₀=0 where:

B₀=A_{0<sub2>—</sub2>Re}A_{00<sub2>—</sub2>Im}−A_{0<sub2>—</sub2>Im}A_{00<sub2>—</sub2>Re}.

The invention provides a multi-band antenna structure for use in a wireless communication system. The antenna structure includes integrated inductive elements and capacitive elements that function as a tuned circuit to allow the antenna structure to operate in multiple frequency ranges. In particular, the capacitive elements electromagnetically couple to the inductive elements. The capacitive elements provide the inductive elements with parallel capacitance at a given set of frequencies, thereby providing the antenna structure with frequency selectivity. At a particular frequency range, the inductive elements act as short circuits, thereby lengthening the radiating elements, which radiate energy at the particular frequency. At another frequency range, the inductive components act as open circuits, virtually shortening the radiating elements in order to radiate the higher frequencies. In this manner, the multi-band antenna structure operates within multiple frequency ranges.

A power supply device includes a battery 1, an output switch 2 connecting the battery 1 to a load 20, and a control circuit 3 controlling the output switch 2. The output switch 2 is a semiconductor switching element 11 having controllable ON resistance. In the power supply device, the ON resistance of the semiconductor switching element 11 is controlled by the control circuit 3 so that the ON resistance in a precharge state is set larger than the ON resistance in an electrically-conducted state. The parallel capacitor 23 of the load 20 is precharged in the precharge state. After the parallel capacitor 23 of the load 20 is precharged, the load 20 is supplied with power from the battery 1 with the semiconductor switching element 11 being brought into the electrically-conducted state in which the ON resistance of the semiconductor switching element 11 is smaller than the precharge state.

The converter includes six pieces of three phase bridge arm including full controlled main switch with diode connected in inverted parallel, input inductance connected between power source and middle point of each phase bridge arm, and output capacitance connected to output end of three phase bridge arm. Characters are that capacitance is connected to six main switches respectively. Resonant inductance is connected to DC bus of three-phase bridge arm and output capacitance. Cascaded circuit of auxiliary switch and clamping capacitance is cross-connected on two ends of resonant inductance. Two ends of the auxiliary switch are connected to diode in inverted parallel as well as connected to capacitance. Features of the converter are simple structure, restraining backward recovery of diode connected in inverted parallel, realization of soft switch and high efficiency of circuit.

Switching of parallel capacitors in an HID bi-level lighting control system is accomplished through use of transient voltage suppression across an electronic relay for discharge of residual charge from a switched capacitor when combined peak voltage exceeds clamping voltage, thereby allowing maximum switch voltage rating to be lower than is possible through the use of conventional switching methods and circuitry. The invention contemplates method and apparatus permitting capacitive switching at voltage levels higher than are possible in conventional capacitive switching arrangements including capacitive switching arrangements used in lighting control systems.

The invention discloses a virtual-capacitor-based power sharing control method for micro-grid inverter parallel connection. The method is characterized in that a voltage amplitude value and a phase angle value are obtained by using a power outer ring of a power outer ring control algorithm; and a virtual capacitor algorithm is added to obtain an output voltage amplitude value and a phase angle instruction, and dual-closed-ring control of the output voltage and the capacitive current is carried out. According to the virtual capacitor algorithm, parallel capacitor characteristics of output terminals of inverters are simulated by a control algorithm and the output voltages and reactive powers of the inverters are adjusted; and a virtual capacitance value is obtained by calculation based on outputted reactive powers of all inverters and a capacitance sagging formula. According to the invention, interconnection communication among inverters and connecting impedance detection are not required; the line impedance voltage drop can be compensated in a self-adaption mode; and reactive power sharing capabilities and output voltage precision of all inverters can be improved.

The invention discloses a soft switching three-phase gird-connected inverter additionally provided with a freewheeling path, which comprises an inverter direct current power supply, a three-phase bridge arm formed by six full-control master switches with antiparallel diodes, and output filter inductors respectively connected between the midpoint of each phase of the bridge arm and an alternating current grid, wherein the three-phase bridge arm is connected with a full-control switch with an antiparallel diode, the full-control switch and the six master switches of the three-phase bridge arm are respectively connected with a capacitor in parallel, an auxiliary switch with an antiparallel diode and a serial branch of a clamp capacitor are accessed between the inverter direct current power supply and a direct current bus of the three-phase bridge arm, and a resonance inductor Lr is bridged at two ends of the serial branch, and the auxiliary switch is connected in parallel with the capacitor. The invention is simple in structure, can suppress the reverse recovery of the diodes, and reduces the electromagnetic interference. All switches of the inverter realize zero-voltage switching-on, thus the inverter has the advantages of little switching loss and high circuit efficiency. The inverter can realize control of power factors and harmonic waves for output grid-connected current, and can be used in a grid-connected inverter in various power supplies.