4580 results about "Dc current" patented technology

A LED driver circuit is disclosed that has the ability to drive a single series string of power LEDs. The LED driver circuit uses a single stage power converter to convert from a universal AC input to a regulated DC current. This single stage power converter current is controlled by a power factor correction unit. Furthermore, the LED driver circuit contains a galvanic isolation barrier that isolates an input, or primary, section from an output, or secondary, section. The LED driver circuit can also include a dimming function, a red, green, blue output function, and a control signal that indicates the LED current and is sent from the secondary to the primary side of the galvanic barrier.

A novel apparatus and method of improving the power efficiency of a digital transmitter for non-constant-amplitude modulation schemes. The power efficiency improvement mechanism of the invention leverages the high efficiency of a switched-mode power supply (SMPS) that supplies the high DC current to the transmitter's power amplifier, while compensating for its limitations using predistortion. The predistortion may be achieved using any suitable technique such as digital signal processing, hardware techniques, etc. A switched mode power supply (i.e. switching regulator) is used to provide a slow form (i.e. reduced bandwidth) of envelope tracking (based on a narrower bandwidth distorted version of the envelope waveform) such that the switching regulator can use a lower switching rate corresponding to the lower bandwidth, thereby obtaining high efficiency in the switching regulator. The resulting AM-AM and AM-PM distortions in the power amplifier are compensated through predistortion of the digital amplitude modulating signal which dictates the envelope at the PA input. Similarly, the phase modulation is also compensated prior to the PA, such that once it undergoes the distortion in the PA, the end result is sufficiently close to the desired phase.

A variable speed wind turbine employing a rotor connected to a multiplicity of synchronous generators with wound field or permanent magnet rotors. A passive rectifier and an inverter are used for power transfer back to the grid. A Turbine Control Unit (TCU) commands a required generator torque based on rotor speed and power output of the turbine inverters. Torque is controlled by regulating the DC current by control of the inverter. A main-shaft-damping filter is provided by measurement of the DC bus voltage. In high winds the turbine remains at a constant average output power through a constant torque command and a varying pitch command to a rotor pitch servo system. A set point is fixed at the inverter output such that output VAR load is minimized running the turbine at very nearly unity power factor. Dynamic VAR and power factor control is provided by a separate VAR apparatus.

A variable speed wind turbine employing a rotor connected to a multiplicity of synchronous generators with wound field or permanent magnet rotors. A passive rectifier and an inverter are used for power transfer back to the grid. A Turbine Control Unit (TCU) commands a required generator torque based on rotor speed and power output of the turbine inverters. Torque is controlled by regulating the DC current by control of the inverter. A main-shaft-damping filter is provided by measurement of the DC bus voltage. In high winds the turbine remains at a constant average output power through a constant torque command and a varying pitch command to a rotor pitch servo system. A set point is fixed at the inverter output such that output VAR load is minimized running the turbine at very nearly unity power factor. Dynamic VAR and power factor control is provided by a separate VAR apparatus.

A combiner box is used to collect direct current from solar panels or other energy sources. The combiner box integrates all means necessary for ground fault detection, current monitoring, voltage monitoring, and power monitoring. The combiner box may include a communication interface suitable for Web enabled monitoring, electronic notifications of system status, and / or remote control of system functions. In one embodiment, the combiner box uses integrated circuits and printed circuit board technology to achieve new efficiencies in manufacturing, installation and system analysis at the string level. A separate hand piece may be used by installers to test the performance of the combiner box, installation of the solar panels, performance of the solar panels and connections between the solar panels and the combiner box.

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.

Secondary resonant pickup coils (102) used in loosely coupled inductive power transfer systems, with resonating capacitors (902) have high Q and could support large circulating currents which may destroy components. A current limit or "safety valve" uses an inductor designed to enter saturation at predetermined resonating currents somewhat above normal working levels. Saturation is immediate and passive. The constant-current characteristic of a loosely coupled, controlled pickup means that if the saturable section is shared by coupling flux and by leakage flux, then on saturation the current source is terminated in the saturated inductor, and little detuning from resonance occurs. Alternatively an external saturable inductor (1101, 1102) may be introduced within the resonant circuit (102 and 902), to detune the circuit away from the system frequency. Alternatively DC current may be passed through a winding to increase saturation of a saturable part of a core. As a result, a fail-safe pickup offering a voltage-limited constant-current output is provided.

An apparatus and method of control for converting DC (direct current) power from a solar photovoltaic source to AC (alternating current) power. A novel DC-to-AC power converter topology and a novel control method are disclosed. This combination of topology and control are very well suited for photovoltaic microinverter applications. Also, a novel variant of this control method is illustrated with a number of known photovoltaic DC-to-AC power converter topologies. The primary function of both control methods is to seek the maximum power point (MPP) of the photovoltaic source with novel, iterative, perturb and observe control algorithms. The control portion of this invention discloses two related control methods, both an improvement over prior art by having greatly improved stability, dynamic response and accuracy.

A directional induction logging tool is provided for measurement while drilling. This tool is preferably placed in a side pocket of a drill collar, and it comprises transmitter and receiver coils and an electromagnetic reflector. The reflector, which may be a layer of highly conductive material placed between the coils and the body of the drill collar, serves to focus the electromagnetic fields generated and sensed by the tool in the direction away from the reflector, thus providing a directional response to formation conductivity with a relatively high depth of investigation. In preferred embodiments of the invention, magnetically permeable cores are placed within the coils to concentrate the magnetic fields that pass through them. Circuitry is described for balancing the mutual inductive coupling of the coils by injecting a direct current signal through one or more of the coils, which alters the magnetic permeability of the core material. The magnitude of the direct current required to achieve a balanced condition may be derived from the quadrature phase component of the return signal. Circuitry is also provided for generating a transmitted signal and for processing the return signals, including digital-to-analog conversion circuitry for providing digital data for transmission to the surface. This tool may be employed to provide real-time directional conductivity information that may be used to detect and follow bed boundaries in geosteering operations.

The subject matter of the present invention is a load breaker arrangement (1) for switching on and off a DC current of a DC current circuit in a photovoltaic plant with a semiconductor switching element (4) to avoid a switching arc, there being provided an electronic control unit (5) configured such that one or more signals are received by the control unit, and the load breaker arrangement (1) being configured such that in at least one current-carrying line of the DC current circuit there is galvanic separation by a switching contact that is automatically controllable by the control unit (5) in the switched-off condition and one or more control signals being transmitted to the load breaker arrangement (1) and a semiconductor switching element (4) interrupting the DC current so that the switching contact is de-energized, wherebythe signals are flaw signals that are received in case of a flaw in the PV generator, inverter or on the AC side, the DC current circuit being automatically switched on or off by the control signals in case of at least one flaw,said arrangement being configured such that, during switch off,said semiconductor switching element (4) is at first closed in a first step,the switching contacts (K1, K2) of a first switching means are opened in a second step for the DC current to flow through said semiconductor switching element (4),said semiconductor switching element (4) being again opened in a third step andswitching contacts (K1, K2) of a second switching means being opened in order to cause galvanic separation to occurand that an additional manually operable load breaker (8) is connected, said manually operable load breaker (8) being a manually breakable DC current connecting system with plug contacts for photovoltaic plants that is provided with an electronic arc quenching system.

A method and apparatus for converting Direct Current (DC) to Alternating Current (AC). The method comprises performing system analysis on at least one of a DC current, DC voltage, or an AC voltage; utilizing the system analysis for selecting at least one conversion parameter; and converting DC to AC utilizing the at least one conversion parameter.

A bidirectional active power conditioner includes a DC side, a bidirectional DC / DC power converter, a DC / AC inverter and an AC side. The DC side electrically connects with a DC source while the AC side electrically connects with a load and an AC source. The bidirectional DC / DC power converter is controlled via high-frequency pulse width modulation (PWM) switching so as to generate a predetermined DC voltage or DC current while the DC / AC inverter is controlled to convert the predetermined DC voltage or DC current into a predetermined AC voltage or AC current.

A low voltage ceiling or wall mounted light fixture for residential and commercial lighting includes a plurality of high lumen white LED lights incorporated within the fixtures, a light color diffusion panel and a household current to low voltage DC converter within the fixture to convert the AC current to low voltage DC current, reducing the power required for illumination without replacement of the LED lights.

A passive harmonic switch mixer is shown that is immune to self mixing of the local oscillator greatly reducing leakage noise, pulling noise, and flicker noise when used in a direct conversion receiver or direct conversion transmitter circuit. The passive harmonic switch mixermixes an input signal received on an input port with an in-phase oscillator signal and a quadrature-phase oscillator signal and outputs an output signal on an output port. Because the quadrature-phase oscillator signal is the in-phase oscillator signal phase shifted by 90 °, the passive harmonic switch mixer operates with a local oscillator running at half the frequency of the carrier frequency of an RF signal. Additionally, because the passive harmonic switch mixer has no active components, the DC current passing through each switch device is reduced and the associated flicker noise of the mixer is also greatly reduced.

The invention relates to a drive circuit for driving an LED array. In order to allow driving the LED array based on an AC current supplied by an electronic ballast circuit for driving a fluorescent lighting device, the invention provides for a power supply sub-circuit converting the supplied AC current to a DC current and at least partially storing energy of the converted DC current for driving the LED array. Further, the power supply sub-circuit is connected / disconnected to / from at least one of first or second terminals in response to the presence / absence of the AC current supplied via a terminal of at least one of the first or second terminals. Accordingly, the power supply sub-circuit is connected to the first and second terminals only when the supplied AC current is simultaneously supplied via a terminal of each of the first and second pair of terminals.

Electronic circuitry for color-mixing in an LED light fixture during AC power dimming is disclosed to achieve adjustable color temperature. According to one embodiment, a dimmable LED light fixture has first, second, and third LED light sources, the first and second LED light sources producing white light, the third LED light source producing colored light, the LED driver configured to power the LED light sources by providing a single-channel variable-DC current source having two output terminals, and a current regulator for maintaining the current in the third LED light source path substantially constant as the LED driver output current is decreased when the AC power is reduced by the dimmer module, thereby altering the color of the light produced by the combination of the LED light sources.

A wireless power system that may align a portable electronic device with an inductive wireless power supply. The induction coils used for transferring power wirelessly may be used as DC electromagnets to align the portable electronic device with the inductive wireless power supply. A DC current may be supplied to the primary coil and to the secondary coil to generate DC electromagnetic fields and attractive force between the primary and secondary coils. This attractive force may be used for alignment.

Current controlled power sources are disclosed that are capable of generating currents in low resistance, high temperature plasmas that are regulated to prevent the generation of excessive currents in the plasma. Current reversing switches are provided that control the flow of a direct current in a plasma chamber between various electrodes. Multiple power sources are provided in association with shunt switches for delivering a plurality of sources of direct current in various directions between electrodes in a plasma chamber. Inductive impedance can be provided in switch paths to cause a source of direct current to flow through a plasma chamber in various directions between electrodes.

An integral method for realizing parallel generation and network reactive power compensation at the same time is based on the transient reactive power theory applying park transfer to transform a three phase inverter output current to a rotation dq coordinate to realize separation of active current and reactive current to convert the DC current of the photovoltaic to AC current by controlling the currents and directions carry out reactive power compensation to the local network. When a photovoltaic battery has enough energy to output, it realizes parallel generation and reactive compensation at the same time, when it stops the output, the inverter compensates the network independently.

A tissue cutting device includes a catheter with a window at its distal tip for admitting tissue into a catheter compartment. A cylindrical cartridge in the compartment has a cutting edge that supports an electrically conductive cutting element, e.g. a band or wire. The cutting element and adjacent tissue can be heated to a selected temperature by generating an electrical current through the cutting element. The catheter is maneuverable to position its distal end near the tissue to be cut. The catheter incorporates a dilatation balloon or other feature to urge the catheter against the tissue, so that at least part of the tissue may enter the compartment through the window. Then, the cartridge is manipulated from the catheter's proximal end to move the cutting edge across the window, cutting the tissue. According to alternative embodiments, the cartridge is either rotated or moved axially relative to the catheter and, in either event may be capable of closing the catheter window when the cut is complete. Further alternatives involve either placing an indifferent electrode on the patient and providing an RF signal via a single conductor to the cutting element for ohmic heating, or providing an RF (or a DC) current through the cutting element and two separate conductors for direct resistive heating of the cutting element.

There is provided a LED array driving apparatus for driving a light emitting array having a plurality of LEDs connected to one another, including: a DC-DC converting part; a current / voltage detecting part detecting a magnitude of a first current flowing through a switching transistor of the DC-DC current converting part to correspondingly output a first current detection voltage, detecting a magnitude of a both-end voltage of the LED array to correspondingly output a LED array detection voltage, and detecting a magnitude of a current flowing through the LED array to correspondingly output a second current detection voltage; and a constant current controlling part controlling an on / off duty of the switching transistor according to the magnitude of the first current detection voltage, the second current detection voltage and the LED array detection voltage detected by the current / voltage detecting part.

A control system controls the operation of at least a first and a second independently controllable LED light member. The control system includes a frame member on which a plurality of electrical components can be mounted, and at least one input port for receiving at least one of a power source and a command signal source capable of sending a command signal to at least one of the first and second LED light members. A first driver member is provided for conducting power to deliver conditioned DC power to the first LED member. A first driver to frame connector removably couples the first driver member to the frame member. A second driver member conditions power to deliver conditioned DC power to the second LED member, and a second driver to frame connector removably couples the first driver member to the frame member. A first external output port is coupled to the first driver, and a second external output port coupled to the second driver. A first multi-channel electrical conductor is coupled to the first external output port for conducting conditioned DC current to the first LED light member; and a second multi-channel electrical conductor conducts conditioned DC current to the second LED light member.

The invention belongs to the technical field of distributed power generation microgrid systems in power systems and relates to a wind-solar-diesel storage isolated microgrid system which comprises a lead-acid battery, one group or multiple groups of photovoltaic battery arrays, a fan, a diesel generator, a microgrid monitoring sub-system, a controllable load and an uncontrollable load, wherein the fan comprises more than one wind turbine generator or more than one group of wind turbine generator set, the lead-acid battery and the photovoltaic battery arrays are merged into a direct current bus bar through all front-stage two-way DC (direct current) / DC converters and connected into an alternating current bus bar through a two-way DC / AC (alternating current) inverter, the diesel generator is merged into the direct current bus bar through an AC / DC current converter, the wind turbine generator set is connected into the alternating current bus bar through an AC / DC / AC converter, the microgrid monitoring sub-system is used for controlling voltage and the frequency in a microgrid to be stable. The invention simultaneously provides a coordinated operation control method for the system. Thewind-solar-diesel storage isolated microgrid system has stronger robustness and flexibility, and can meet the long-term high-efficient stable operation requirement of the isolated microgrid system.

In a power line takeoff clamp assembly and method of use thereof an electrical power distribution line is clamped to a body of the clamp assembly. A power takeoff supported by the body clamped to the power line generates direct current from alternating current flowing in the power line. One or more sensors supported by the body clamped to the power line sense one or more values related to an electrical current flowing in a power line. A wireless transceiver supported by the body clamped to the power line communicates data regarding the one or more sensed values. Each sensor and the wireless transceiver utilize direct current generated by the power takeoff for the operation thereof.

An apparatus including an alternator that is drivable by an engine for producing a first AC electric current, a rectifier in electrical communication with the alternator for producing a DC electric current, an inverter in electrical communication with the rectifier for producing a second AC electric current where the second AC electric current having an acceptable frequency and / or voltage, and the inverter in electrical communication with one or more electric loads responsive to the second AC electric current, and an energy storage device that is able to electrically couple to the alternator, rectifier, and / or inverter.

A single-stage electronic ballast device outputs a square wave current to drive an HID lamp, which includes a rectifying and power factor correction unit, a bridge converter and a controller circuit. The rectifying and power factor correction unit has an input connected to an AC power source to rectify an AC power to a DC power. The bridge converter comprises two bridge arms formed by four switches, load terminals defined by midpoints of the two bridge arms and the HID lamp is connected between the load terminals. The bridge converter converts DC current to square wave current to drive the HID lamp with power control. The load terminals are selectively connected to output of the rectifying and power factor correction unit to adjust waveform of input current for higher power factor. The controller circuit has output connected to DC link voltage terminal and load terminal of the bridge converter.