305 results about "Dc ac converter" patented technology

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 three-stage electronic ballast for metal halide lamps mainly comprises a step-up converter, a step-down converter and a full-bridge DC-AC converter, wherein the step-down converter operates an inductor in a continuous boundary current mode to achieve reducing power loss and enhancing efficiency. Equipped with a micro processor, the electronic ballast further possesses the function of power regulation. The electronic ballast can be added with various protective functions without complex control circuits and sensing elements, thereby becoming a high-quality and low-cost electronic ballast for metal halide lamps.

A constant current control is performed by PWM, and an analog burst control and a digital burst control are made selectable. The burst controls are selected in the following manner. A capacitor is selected as an element which is to be connected to a triangular signal oscillator circuit, to generate a triangular signal, thereby setting the analog burst control. A resistor is selected as the element to generate a constant voltage, thereby setting the digital burst control. A controller IC is used commonly in both the burst controls.

A method of activating a Multi-String inverter for photovoltaic generators (1a, 1b) of a photovoltaic plant (6), the Multi-String inverter incorporating on the input side a separate DC-DC converter (2a, 2b) for each generator string (photovoltaic generator) (1a, 1b) and each output of the DC-DC converters (2a, 2b) being connected in parallel and to an input of a DC-AC converter (3) and the DC-AC converter (3) being connected with an alternating current mains (4) for feeding into the mains aims at improving efficiency. This is achieved in that one or several electrical variables, namely input current, input voltage and / or input power are measured at each DC-DC converter (2a, 2b) and at least one of the DC-DC converters (2a, 2b) changing its operating condition as a is function of this measurement when a limit value and / or a range is exceeded in such a manner that its power loss is reduced so that the energy yield of the photovoltaic plant (6) is increased.

A method for controlling a DC-transmission link for transmitting electric power from a power production unit connected to an AC-DC converter at a first side of the DC-transmission link to a utility grid connected to a DC-AC converter at a second side of the DC-transmission link is provided. The method includes: obtaining a DC voltage signal indicative of a DC voltage at the DC transmission link; controlling the AC-DC converter such that an AC voltage at an AC side of the AC-DC converter is adjusted based on the DC voltage signal. Further, an apparatus for controlling a DC-transmission link is provided.

The subject matter of the invention is an inverter (3), more specifically for use in a photovoltaic plant (1) with a direct voltage input (connection terminals 4; 5) for connection to a generator (2) and an alternating voltage output (connection terminals 7; 8) for feeding into an energy supply network (6) as well as with a DC-AC converter (12) with semiconductor switch elements (15) and an intermediate circuit (11), at least one short-circuit switch element (18) being connected in parallel to the generator (2), so that the voltage will not exceed a maximum voltage value neither at the connection terminals (4; 5) of the generator (2) nor between the connection terminals (9; 10) of the inverter. This is achieved in that the inverter (3) comprises, in the intermediate circuit (12), a buffer capacitor (14) that is connected to the generator (2) through a protection diode (17) so that said buffer capacitor (14) will not be discharged upon actuation of the short-circuit switch element (18), the generator (2) working according to a clock rate in the short-circuit mode of operation.

To provide a DC-DC converter allowing miniaturization of a voltage transformer without fear of reducing conversion efficiency due to saturation of the transformer and allowing enhancement of conversion efficiency by suppressing switching loss. An LC resonance circuit 3 is inserted on the secondary side of a transformer 1. When driving means 4 alternately turn on and off a pair of switching means 2-1, 2-2, an output is obtained on the secondary side via the transformer 1. A current transformer 5 for current detection, a current value detection portion 6 and a current value comparison portion 7 detect a difference between each resonance current value per half cycle due to the operation of the LC resonance circuit 3. In response to its result, the drive means 4 regulate automatically on-state duty ratio of the switching means 2-1, 2-2 so as to align the resonance current values per half cycle.

The invention relates to a controller of full-power alternative-direct converter used in wind generation, wherein the alternative-direct converter is formed by network converter and the convert of generator; the used generator is a permanent-magnetic generator; the rotor is in permanent-magnetic structure, without external magnetic activate power supply; two convert loops both uses the PWM converters operating in four quadrants, based on full-control element, which can improve the dynamic response, reduce cost and impact, realize bidirectional transmission of electricity, and realize generating via power factor sine wave current parallel network; and the invention uses improved direct torque technique to control the converter, to confirm the sine wave change of input current at the stator, with quick response, low vibration, torque dynamic control and wide speed adjust range.

An electrodeless discharge lamp operating device including an electrodeless discharge lamp 3 and a ballast circuit 4, wherein the ballast circuit 4 includes: an AC-DC converter 5 for converting a phase-controlled AC voltage into a DC voltage; a DC-AC converter 6 formed so as to intermittently drive the electrodeless discharge lamp 3 due to the existence of an operating period during which a high-frequency voltage is applied to the electrodeless discharge lamp 3 so that the electrodeless discharge lamp 3 is operated, and an extinguishing period during which the generation of the high-frequency voltage is stopped so that the electrodeless discharge lamp 3 is extinguished; and a dimming controller 7 for detecting the turn-on of the phase-controlled AC voltage, for outputting an intermittent command signal that changes the ratio between the operating period and the extinguishing period to the DC-AC converter 6, and for outputting a signal that maintains an intermittent dimmable operating state even if dimming state is in full illumination.

A power supply apparatus, such as an on-line UPS, includes an AC / DC converter circuit having an input configured to be coupled to an AC source, a DC / AC converter circuit having an input coupled to an output of the AC / DC converter circuit by a DC link, and a bypass circuit operative to couple and decouple the output of the DC / AC converter circuit to and from the input of the AC / DC converter circuit. Power is transferred from the output of DC / AC converter circuit via the bypass circuit to conduct a test of the apparatus, such as a factory or field load test. For example, power may be circulated around a loop including the AC / DC converter circuit, the DC / AC converter circuit and the bypass circuit to conduct the test in order to test these components under load. A status of such components may be determined responsive to the test. In further embodiments, such components may be calibrated responsive to the test.

A non-outage power supply system comprises three-phase ac input terminals and three-phase ac output terminals, between which there are sequentially connected a three-phase ac-to-dc converter circuit, a capacitor, and a three-phase dc-to-ac converter circuit. A bypass switch is connected between a preselected one of the three-phase ac input terminals and a preselected one of the three-phase ac output terminals. A bypass switch control circuit holds the bypass switch closed when the three-phase ac inputs are in phase with the three-phase ac outputs, and open when they are not. Part or all of the effective current demanded by the load bypasses the three-phase dc-to-ac converter circuit when the bypass switch is closed, with a consequent reduction of power loss.

This invention discloses a dual-feed AC-DC-AC converter control structure for wind power generation, and the rotor exciting magnetic converter using the fuzzy PI adaptive control strategy of current inner loop. When the generator no-load networking, the current inner loop uses the conventional PI regulator, and after networking, as to three modes, sub-synchronization, synchronization, super-synchronous, it uses fuzzy adaptive PI control. The network-side converter uses SPWM control strategy which fixed switching frequency and combining electric network electromotive front-feed. In the invention, both converting processes use four-quadrant operation PWM converters based on full-controlled devices, so it can not only improve the system dynamic response, reduce wastage and impact, achieve the two-way electric transmission, but also it can achieve wind power generation network side unit power factor sinusoidal current networking power generation operating.

A railway power conditioner includes a DC-AC converter and a AC-DC converter for performing power conversion between AC power and DC power, a DC bus connected between the DC-AC converter and the AC-DC converter; a single-phase isolation transformer coupled to an output of the AC-DC converter and a coupling capacitor connected to the DC-AC converter.

The invention discloses a single-phase combined in-phase power supply and transformation structure mainly comprising a traction transformer and a CPD. In the CPD, a high-voltage matching transformer primary side and a traction transformer primary side form an SCOTT connected group, a secondary side winding of the CPD is connected to the incoming end of an AC-DC-AC converter, and the outgoing end of the AC-DC-AC converter is connected with the primary side of a traction matching transformer. A secondary side winding of the traction transformer and the secondary side winding of the traction matching transformer are equal in voltage amplitude and phase and both connected with a traction busbar; traction load calculated capacity is equal to the sum of traction transformer calculated capacity and CPD calculated capacity, the traction transformer is responsible for main power supply, and the CPD calculated capacity is determined by the capacity of traction load which caused exceeding three-phase voltage unbalance. The single-phase combined in-phase power supply and transformation structure has the advantages that optima configuration of traction power supply resources is realized and energy conservation is better.

An electrodeless self-ballasted fluorescent lamp includes an electrodeless fluorescent lamp 3, a ballast circuit 4 and a lamp base which are formed as one unit. The ballast circuit 4 includes: an AC-DC converter 5; a DC-AC converter 6 formed so as to intermittently drive the electrodeless fluorescent lamp 3; and a dimming controller 7 formed so as to detect the turn-on of a phase-controlled AC voltage and output an intermittent command signal for changing the ratio between an operating period and an extinguishing period to the DC-AC converter 6. Furthermore, the dimming controller 7 is formed so as to output a signal for extinguishing the electrodeless fluorescent lamp 3 before the operation thereof becomes unstable.

An energy efficient and highly versatile electrically-powered air conditioning and heating system for mobile vehicles. Multiple variable-speed compressors operate in series and parallel modes giving an exceptionally wide range of operating capacity making the system suitable for combined on-highway and no-idle use in trucks. In series mode, the single-stage compressors function like a two-stage compressors for increased energy efficiency. A unique power control and storage system has multi-voltage input and output capability without the use of DC-DC or DC-AC converters. A battery management system is incorporated which is compatible with all advanced battery technologies and offers cell-level charge and discharge control.

A dc-ac converter capable of supplying a finely regulated ac drive voltage to a load is provided. For this purpose, the converter includes, in a primary winding of a transformer, a full-bridge or half-bridge type semiconductor switch circuit whose switches can be controlled by pulse-width modulation. Transformer has a secondary winding for connection with a load. Based on PWM signals and by use of adequate switching logics for controlling multiple semiconductor switches, sophisticated control including zero-current switching and penetrating current prevention can be effected. Moreover, by means of regulated burst control of the ratio of on-duty period to off-duty period together with pulse-width modulation control, power supplied to the load can be regulated over a wide range beyond the limits of control obtained by the pulse-width modulation.

The invention discloses a front cabin steel-frame structure of an electric vehicle and a front cabin. The front cabin steel-frame structure of the electric vehicle consists of main components: a front cabin left longitudinal beam, a front cabin right longitudinal beam, a transverse connecting beam framework and the like. Moreover, the front cabin steel-frame structure and a subframe are combined to further form upper and lower layer structures of the front cabin of the electric vehicle. An upper layer structure is used for installing various modules: a motor controller, a high and low voltage converter, a direct current-alternating current converter, a charger and the like, and thus, the condition that the modules are arranged in front of or at the rear of a power assembly is avoided, and therefore, an energy absorption space when forward collision of the vehicle occurs is increased, and the safety performance of the vehicle is improved. A lower layer structure is used for installing a motor and a gearbox, and therefore, the danger that the strength is excessively low due to the fact that a suspension device of the power assembly has to be installed on the longitudinal beams to form a cantilever beam structure is avoided, and a flexible space is provided to the arrangement position of the suspension device.

A double-ended, DC-AC converter supplies AC power to a load, such as a cold cathode fluorescent lamp used to back-light a liquid crystal display. First and second converter stages generate respective first and second sinusoidal voltages having the same frequency and amplitude, but having a controlled phase difference therebetween. By employing a voltage controlled delay circuit to control the phase difference between the first and second sinusoidal voltages, the converter is able to vary the amplitude of the composite voltage differential produced across the opposite ends of the load. The converter may be either voltage fed or current fed.

An energy storage device system for a primary frequency modulation and automatic generation control (AGC) auxiliary regulation technology comprises a power generation set, a transformer, a power grid, a DC-AC converter and energy storage battery packs and is characterized in that a multi-port DC-DC converter is also arranged, so that connection ports of a plurality of energy storage battery packs are connected with respective port of the DC-DC converter, and at least one supercapacitor is also connected with the respective port of the DC-DC converter; and moreover, a load allocation system is used for receiving a dispatched AGC instruction or forming a load instruction according to a frequency of the power grid, the instruction is divided into two paths, one path passes through an energy management system to be connected with the multi-port DC-DC converter and the DC-AC converter, and the other path is connected with a distributed control system (DCS) and digital electric hydraulic (DEH) control system of the generation set to control the power generation set to work. Therefore, the peak load regulation capability of a power system can be improved, the primary frequency regulation ability and the AGC response capability of a coal-fired unit are improved, the stable running of a power plant is ensured, and energy is saved.

A method of operating a resonant DC-DC converter is provided where the resonant DC-DC converter includes a high voltage boost LLC circuit. The method includes providing variable power flow control to the LLC circuit with externally determined input and output voltages using frequency control. Frequency control is applied such that it emulates different loading conditions. For fixed input and output voltages this corresponds to operating along horizontal curves on the voltage gain compared to the switching frequency operating plane. A DC-DC converter is also provided including (A) a low voltage full-bridge or half-bridge DC-AC converter; (B) an LLC resonant tank; (C) a high voltage AC-DC converter or rectifier; and (D) a high voltage controllable switch; wherein the high voltage controllable switch is controllable to regulate power flow from an input to an output of the DC-DC converter based on an externally determined voltage gain ratio, wherein the LLC resonant lank operates with a minimum boosting having an effective value above unity over the entire operating range. A method of designing a resonant DC-DC converter for high voltage boost ratio is also provided.