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6163 results about "Current source" patented technology

A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. A current source is the dual of a voltage source. The term current sink is sometimes used for sources fed from a negative voltage supply. Figure 1 shows the schematic symbol for an ideal current source driving a resistive load. There are two types. An independent current source (or sink) delivers a constant current. A dependent current source delivers a current which is proportional to some other voltage or current in the circuit.

Transformerless static voltage inverter for battery systems

A static inverter for a battery of elementary, current sources or cells electrically in series and a number N of intermediate voltage taps along the chain of elementary DC current sources, wherein the number of elementary cells comprised between an intermediate tap and another intermediate tap adjacent to it or an end terminal of said chain is proportionate to the amplitude in the respective phase interval of a number N of discretization phases of the waveform of the AC voltage to be output in a quadrant; is implemented by arranging for: a number N of power switches each connecting a respective intermediate tap and a first end terminal of a first polarity of said chain of elementary cells in series to a common circuit node of said first polarity; an output bridge stage constituted by at least four power switches controlled in pairs for switching the current paths through the bridge stage, having a first pair of nodes coupled to said common circuit node of said first plurality and to the other end terminal of polarity opposite to said first polarity of said chain of elementary cells, respectively, and a second pair of nodes constituting an AC output; and a control circuit sequentially and cyclically turning on, in a continuous manner, one switch at the time of said N switches; each for a phase interval of 1/(4N) times the period of said AC output, and alternately tuning on by pairs said four power switches of said output bridge stage at every half a period.

Photovoltaic power plant with distributed DC-to-DC power converters

A solar photovoltaic plant is disclosed where a number of distributed DC-to-DC converters are used in conjunction with a central DC-to-AC converter. Each DC-to-DC converter is dedicated to a portion of the photovoltaic array and tracks the maximum power point voltage thereof. The DC-to-DC converters also boost the photovoltaic voltage and regulate a DC output current for transmission to the central DC-to-AC converter. Five distinct advantages are had over the prior art. First, efficiencies in intra-field power collection are greatly improved by transferring power at higher DC voltages. Second, the number of independent photovoltaic maximum power point trackers in the power plant can be increased, in a cost effective manner, to optimize the overall photovoltaic array energy harvest. Third, each DC-to-DC converter output “looks” like a current source at the input of the DC-to-AC converter and therefore can be easily paralleled. Fourth, the current source nature of the DC-to-DC converter outputs enables the DC-to-AC converter to operate with a minimum, fixed DC bus voltage to provide maximum DC-to-AC power conversion efficiencies. And fifth, each distributed DC-to-DC converter can isolate a faulted portion of the photovoltaic array while the remainder of the array continues producing power.

Controlled downhole chemical injection

A petroleum well having a well casing, a production tubing, a source of time-varying current, a downhole chemical injection device, and a downhole induction choke. The casing extends within a wellbore of the well. The tubing extends within the casing. The current source is located at the surface. The current source is electrically connected to, and adapted to output a time-varying current into, the tubing and/or the casing, which act as electrical conductors for providing downhole power and/or communications. The injection device having a communications and control module, a chemical container, and an electrically controllable chemical injector. The communications and control module is electrically connected to the tubing and/or the casing. The chemical injector is electrically connected to the communications and control module, and is in fluid communication with the chemical container. The downhole induction choke is located about a portion of the tubing and/or the casing. The chemical injector is electrically connected to the communications and control module, and is in fluid communication with the chemical container. The downhole induction choke is located about a portion of the tubing and/or the casing. The induction choke is adapted to route part of the electrical current through the communications and control module by creating a voltage potential between one side of the induction choke and another side of the induction choke. The communications and control module is electrically connected across the voltage potential. Also, a method is provided for controllably injecting a chemical into the well downhole, which may be used to: improve lift efficiency with a foaming agent, prevent deposition of solids with a paraffin solvent, improve a flow characteristic of the flow stream with a surfactant, prevent corrosion with a corrosion inhibitor, and/or prevent scaling with scale preventers.

Device for non-dissipative measurement of the current in an inductor

The invention relates to a device for measuring current in an inductor, which device is intended to be connected in parallel with said inductor, comprising two terminals A and B. The device comprises: a network in parallel with the inductor and connected to the terminals A and B having a resistor R2 in series with a resistor R1 in parallel with a capacitor C1; a voltage offset circuit having a DC voltage generator E connected in parallel with an offset resistor (Roffset) in series with two resistors in parallel R3 and R4, the positive pole of this voltage source being connected to terminal B of the inductor; a temperature compensation circuit comprising a current source controlled as a function of the temperature, one of the two terminals of the current source being connected to the negative pole of the generator E, the other terminal of the current source being connected to different points of the measurement device according to the direction of variation of the current of the source as a function of the temperature. The measurement of voltage Vmes, the image of the current I in the inductor 12, is performed between the common point between the resistors R1, R2 of the network and the common point between the offset resistor and the two resistors R3 and R4.

Capacitively coupled plasma reactor with magnetic plasma control

A plasma reactor includes a vacuum enclosure including a side wall and a ceiling defining a vacuum chamber, and a workpiece support within the chamber and facing the ceiling for supporting a planar workpiece, the workpiece support and the ceiling together defining a processing region between the workpiece support and the ceiling. Process gas inlets furnish a process gas into the chamber. A plasma source power electrode is connected to an RF power generator for capacitively coupling plasma source power into the chamber for maintaining a plasma within the chamber. The reactor further includes at least a first overhead solenoidal electromagnet adjacent the ceiling, the overhead solenoidal electromagnet, the ceiling, the sidewall and the workpiece support being located along a common axis of symmetry. A current source is connected to the first solenoidal electromagnet and furnishes a first electric current in the first solenoidal electromagnet whereby to generate within the chamber a magnetic field which is a function of the first electric current, the first electric current having a value such that the magnetic field increases uniformity of plasma ion density radial distribution about the axis of symmetry near a surface of the workpiece support.

Input device for portable digital computers and portable digital computer with a multi-functional mouse

The invention relates to a portable digital Computer with an in-built coupling device which is arranged in order to receive mouse Signals from a radio mouse provided with a battery and fed by said battery. Said digital Computer comprises an in-built current source and an electric interface which is installed in a fixed manner and which is connected to the current source, the electric interface being arranged such that the battery can be charged. The invention also relates to an input device for a portable digital Computer comprising a radio mouse and an additional slide pad which is arranged on the top side of said radio mouse. The invention further relates to a special coupling bay comprising a recess which is a notebook. Said coupling bay is used for mechanically coupling a Cursor control device which is disposed below a notebook keyboard and in order to reconfigure the Cursor control device in a rear-sided Operation in order to use a notebook in a book-type and handheld form, whereby a flat mouse with annular-shaped finger Supports is provided in order to improve the handling and Operation thereof, in addition to a Cursor control device which is provided with an identification and locking function. Additionally, a notebook is disclosed, comprising a decoupling Cursor control device and a keyboard which can be decoupled. A desktop PC can be configured by means of a configuration via a hinge foldable functional part of a notebook.

Photovoltaic units, methods of operating photovoltaic units and controllers therefor

The present invention relates to the field of photovoltaic systems with solar cell (s) or modules having insolation differences or mismatch. Each solar module is formed by placing a large number of solar cells in series. The PV system is then formed by placing a number of solar modules in series in a string and sometimes by placing multiple strings of series-connected solar modules in parallel, depending on the desired output voltage and power range of the PV system. In practical cases, differences will exist between output powers of the solar cells in the various modules, e.g. due to (part of) the modules being temporarily shaded, pollution on one or more solar cells, or even spread in solar-cell behaviour that may become worse during aging. Due to the current-source-type behaviour of solar cells and their series connection these differences will lead to a relatively large drop in output power coming from the PV system. This invention addresses this problem by adding DC-DC converters (803) on a single or multiple solar-cell level that source or sink difference currents thereby increasing the output power of the complete PV system. In embodiments, the efficiency of photovoltaic systems with solar cell (s) or modules is improved by compensating for output-power loss caused by insolation difference and mismatch.
Owner:NXP BV
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