25041results about "Ac-dc conversion" patented technology

The invention includes an electric machine having a rotor, stator and at least one winding in the stator adapted to conduct a current, and a secondary winding, electrically isolated from the first winding and inductively coupled to the first winding, which may be used to control at least one of the output voltage and current of the first winding.

The invention discloses a two-bed duplex tube medical diagnosis X-ray high frequency high voltage generator, which comprises a power supply and a central control unit, and also comprises a high frequency inverter circuit, a pulse-width modulation drive circuit and a high voltage commutation circuit. The generator converts the industrial power supply into two way high frequency high voltage, and then obtains positive end DC high voltage and negative end DC high voltage after the rectification and the filter to supply an X-ray pipet for working. Because the frequency is high and the high voltage ripple after the rectification and the filter is minimum, causing the X-ray pipet of a radiographic table and the X-ray pipet of an electric perspective table to work in turn under the condition of arranging only one set of high voltage supply. The equipment investment is saved, and the work of using the X-ray diagnosis for the medical staff is convenient. Being served as the high voltage supply, the invention is also suitable for the safety detection fields such as the industrial fault detection, the civil aviation, the station, the custom, etc., and supplies the stable high quality high voltage for the equipment.

The invention discloses a medical diagnosis X-ray high frequency high pressure generator, comprising a power supply, a central control unit, a high frequency inverter circuit, a pulse width modulation driving circuit and a high pressure transform and high pressure output circuit. The generator transforms the industrial power to two ways of high frequency and high pressure, a positive direct current high pressure and a negative direct current high pressure are obtained through rectifying and wave-filtering to provide an X-ray ball tube to work. As the frequency is high, the ripple of the rectified and wave-filtered high electric pressure is tiny, and the X-ray quality projected by the X-ray ball tube is high, and the clearance of photos of the perspective and photograph is also high. The X-ray ball tube of a photograph bed or the X-ray ball tube of an electric perspective bed can work if allocated with the high pressure power. The invention is convenient for the medical staff to use the X-ray to do the work of diagnosing diseases. As the high pressure power supply, the invention is also suitable in the safety inspection fields such as industrial flaw detection, civil aviation, station and customs etc, and provides a stable and high qualified high pressure power supply for the equipments.

A system and method for DC to AC conversion in a power generating array. The system and method includes a number of inverters coupled to a group of solar panels. A group controller coordinates operation of the inverters for interleaved switching of the inverters. The group controller communicates via a local area network, a wireless network, or both, to coordinate operation with additional groups of inverters coupled in parallel with additional solar panels.

A modular apparatus for and method of alternating current photovoltaic power generation comprising via a photovoltaic module, generating power in the form of direct current; and converting direct current to alternating current and exporting power via one or more power conversion and transfer units attached to the module, each unit comprising a unitary housing extending a length or width of the module, which housing comprises: contact means for receiving direct current from the module; one or more direct current-to-alternating current inverters; an alternating current bus; and contact means for receiving alternating current from the one or more inverters.

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 power pick-up for an Inductively Coupled Power Transfer (ICPT) system is provided having a resonant pick up circuit. The natural frequency of the pick-up circuit may be varied by controlling the conductance or capacitance of a variable reactive in the resonant circuit. The load being supplied by the pick-up circuit is sensed, and the effective capacitance or inductance of the variable reactive component is controlled to vary the natural resonant frequency of the pick-up circuit to thereby control the power flow into the pick-up to satisfy the power required by the load.

An inductive power transfer system (1) comprises a primary unit (10) operable to generate an electromagnetic field and at least one secondary device (30), separable from the primary unit, and adapted to couple with the field when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween. The system detects if there is a substantial difference between, on the one hand, a power drawn from the primary unit and, on the other hand, a power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices. Following such detection, the system restricts or stops the inductive power supply from the primary unit. Such a system can detect the presence of unwanted parasitic loads in the vicinity of the primary unit reliably.

Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and/or phases, then the energy is transferred out of the inductor to one or more output portals and/or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor/capacitor cycle, thereby maximizing inductor/capacitor utilization as well as providing for optimum converter operation with high input/output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

A new current loop control system method is proposed for a single-phase grid-tie power conditioning system that can be used under a standalone or a grid-tie mode. This type of inverter utilizes an inductor-capacitor-inductor (LCL) filter as the interface in between inverter and the utility grid. The first set of inductor-capacitor (LC) can be used in the standalone mode, and the complete LCL can be used for the grid-tie mode. A new admittance compensation technique is proposed for the controller design to avoid low stability margin while maintaining sufficient gain at the fundamental frequency. The proposed current loop controller system and admittance compensation technique have been simulated and tested. Simulation results indicate that without the admittance path compensation, the current loop controller output duty cycle is largely offset by an undesired admittance path. At the initial simulation cycle, the power flow may be erratically fed back to the inverter causing catastrophic failure. With admittance path compensation, the output power shows a steady-state offset that matches the design value. Experimental results show that the inverter is capable of both a standalone and a grid-tie connection mode using the LCL filter configuration.

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.

A method and apparatus for converting DC input power to AC output power. The apparatus comprises a conversion module comprising an input capacitor, and a first feedback loop for determining a maximum power point (MPP) and operating the conversion module proximate the MPP. The apparatus additionally comprises a second feedback loop for determining a difference in energy storage and delivery by the input capacitor, producing an error signal indicative of the difference, and coupling the error signal to the first feedback loop to adjust at least one operating parameter of the conversion module to drive toward the MPP.

An adaptive electric car or other vehicle with potentially better performance—power, efficiency, range—than a gasoline vehicle, at a competitive cost. The motor control system can dynamically adapt to the vehicle's operating conditions (starting, accelerating, turning, braking, cruising at high speeds) and other inputs and parameters. That consistently provides better performance. Isolating the vehicle's motor or generator electromagnetic circuits allows effective control of more independent parameters. That gives great freedom to optimize. Adaptive motors and generators for an electric vehicle are cheaper, smaller, lighter, more powerful, and more efficient than conventional designs. An electric vehicle with in-wheel adaptive motors delivers high power with low unsprung mass and high torque and power-density. Total energy management of the vehicles entire electrical system allows for large-scale optimization. An adaptive architecture improves performance of a wide variety of vehicles, particularly those that need optimal efficiency over a range of operating conditions.

An electricity charging module using a hysteresis switch includes a storage capacitor that preliminarily stores electrical energy supplied from an external power source, a charging unit for preventing over-charging or over-discharging through monitoring of the charging state of the rechargeable battery, and a hysteresis switch that has a larger turn-on voltage level than the turn-off voltage level, and located between the storage capacitor and the charging unit, thereby electrically connecting or disconnecting the storage capacitor with the charging unit. The hysteresis switch includes a first voltage dividing resistor pair that divides the voltage of an external power source by the resistance ratio of the first voltage dividing resistor pair, a second voltage dividing resistor pair whose one end is connected to a positive electrode terminal of the external power source, a first switching device whose control terminal is connected to the junction of the voltage dividing resistors of the second voltage dividing resistor pair, a second switching device whose control terminal is connected to the junction of the voltage dividing resistors of the first voltage dividing resistor pair, and a resistor that is connected to the junction between the first electrode terminal of the second switching device and the junction of the voltage dividing resistors of the first voltage dividing resistor pair.

This invention is generally concerned with power supply circuits, and more particularly, with circuits to supply power to a mains supply, such as domestic grid mains, from a photovoltaic device. A photovoltaic power conditioning circuit for providing power from a photovoltaic device to an alternating current mains power supply line, the circuit comprising: a DC input to receive DC power from said photovoltaic device; an AC output configured for direct connection to said AC mains power supply line; a DC-to-AC converter coupled to said DC input and to said AC output to convert DC power from said photovoltaic device to AC power for output onto said power supply line; and an electronic controller directly coupled to said power supply line to measure a voltage of said power supply line and a current in said supply line and to control said DC-to-AC converter responsive to said measuring.

In a circuit apparatus for transformerless conversion of an electric direct voltage of a two-pole direct voltage source (1) connected to ground having a first voltage pole (+) and a second voltage pole (−) into an alternating voltage, hazardous capacitive leakage currents are avoided by connecting the direct voltage source (1) to ground and the DC-AC converter (400) is operated at a controlled intermediate circuit voltage, a DC-DC converter stage (300) being connected between the direct voltage source (1) and the DC-AC converter (400), said DC-DC converter stage providing at its output a +/− voltage that is symmetrical with respect to the grounding point, two series-connected capacitors (41, 42) having the same polarity and being connected to ground at their connecting point (V) and controlled are charged by two buck-boost choppers (100, 200) connected one behind the other.

A battery charging and/or DC power supply circuitry employs a control circuit through an SCR drive circuit and an MOS drive circuit to control when to turn on/off a semiconductor switch unit and to turn on the semiconductor switch unit while an initial section of each positive half wave of an AC power source and an terminating section of the same are located below a predetermined level for intercepting partial power for charging. While charging a battery, the circuitry is lightweight, small-sized, and to enhance the life of the battery. While being a DC power supply, the circuitry is small-sized, high-efficiency, and low-cost.