162 results about "AC/AC converter" patented technology

An ac / ac converter for accepting a pulsating dc input with encoded sinusoidal modulation and providing a multiphase modulated output. The converter comprises a bridge including a plurality of switches having switch legs for modulating the pulsating dc input at a carrier frequency over a plurality of phases. The bridge is coupled at one end to a pulsating dc source and coupled at another end to a modulated signal output. A controller is provided for the plurality of switches for causing, for each of the plurality of phases, under unity power factor, one of the switch legs to modulate the pulsating dc input at the carrier frequency while the other switch legs do not modulate the pulsating dc input at the carrier frequency.

An ac / ac converter for accepting a pulsating dc input with encoded sinusoidal modulation and providing a multiphase modulated output. The converter comprises a bridge including a plurality of switches having switch legs for modulating the pulsating dc input at a carrier frequency over a plurality of phases. The bridge is coupled at one end to a pulsating dc source and coupled at another end to a modulated signal output. A controller is provided for the plurality of switches for causing, for each of the plurality of phases, under unity power factor, one of the switch legs to modulate the pulsating dc input at the carrier frequency while the other switch legs do not modulate the pulsating dc input at the carrier frequency.

An AC-AC Converter for an AC source which in one embodiment has a first rectifier section rectifying the AC source into a first pulsed DC link voltage signal and a high frequency modulating section coupled to the first pulsed DC link voltage signal and producing a high frequency AC voltage signal. A high frequency transformer is coupled to the high frequency AC voltage signal producing a transformed high frequency AC signal. There is a second rectifier section coupled to the transformed high frequency AC signal and producing a second pulsed DC voltage signal and an unfolder section coupled to the second pulsed DC voltage signal and producing an output AC signal.

Method for operating an ac / ac converter circuit for a high-frequency-link converter. The ac / ac converter circuit converts an ac input voltage to an ac output voltage. When the ac input voltage is zero, each of a pair of switches for both first and second arms are caused to be on. Current flows through the first arm along a first direction and through the second arm along a second, opposite direction. Next, when the ac input voltage is zero, a selected switch in the second arm is caused to be turned off. The position of the switches can be maintained as the ac input voltage transitions to a dc level, reaches the dc level, approaches zero, and again reaches zero. When the ac input voltage again reaches zero, the selected switch for the second arm is caused to be turned on.

A hybrid transformer is provided that includes an electromagnetic transformer and an AC-AC converter with a DC bridge. The AC-AC converter is operable to keep the input voltage and current of the hybrid transformer substantially in phase and to reduce fluctuation in the output voltage of the hybrid transformer in the event of an increase or decrease in the input voltage.

A novel power conditioning converter which provides a significant reduction in input current ripple (<1%), with efficiency above 90% and reduced thermal management is proposed. The converter in discussion has a sort-switched, multilevel, high frequency converter, which acts as an interface between the dc / dc boost and the ac / ac converter. This paper presents a detailed description of the operation of the converter and highlights the important features and advantages. SABER simulation results are presented to provide an improved understanding of the switching mechanisms. A discussion on the implementation of the converter and the status of ongoing work is presented.

The present invention discloses a non-isolated AC-AC three-level AC-AC converter which has a structure comprising an input filter, a multilevel converter and an output filter connected in turn. Wherein the multilevel converter is composed of a basic constitution unit of two capacitors clamping, an energy-storage inductor and an energy-storage capicitor which are constitued for converting the input voltage to three output levels; the basic constitution unit is composed of a four quadrants power switch and a clamping capicitor. By different combinations with the input filter, basic constitution unit and output filter, a circuit topology family for non-isolated AC-AC three-level AC-AC converter including Boost type, Buck-Boost type, Cuk type, Sepic type and Zeta type. The invention with improved converting effiency, power density, reduced volume and weight as well as input side power factor is fit for high voltage AC-AC electric power converting, due to the reduced volume and weight of the output filter and improved output waveform quality, the application fields of three-level AC-AC converter can be widened.

An A / A inverter in high frequency AC link belongs to eletric power and electronic inverting technique which includes input cycle inverter, high frequency transformer or high frequency energy accumulation transformer, output cycle inverter as well as input and output filtering circuits. It can invert one kind frequency of AC electricity to another kind current electricity with the same frequency (or diffeent frequency) so that it has the advantages of circuit topology in simple power invertion in two stages, power circuit in double direction, modification of current wave shape at net side and power factor as well as the critical technique established for electronic transformer, sine AC stabilizer and variable frequency power source.

This invention discloses an AC-AC three-level converter based on normal converter, in which, the circuit of the converter is composed of an input high voltage AC supply, an input filter, a multi-level converter, a HF transformer, a cycle converter, an output filter and output AC load, in which, the multi-level converter is composed of one or many basic units to convert the input voltage to multiple output levels, said basic unit is made up of two four quadrant power switches and one four-quadrant clamp power switch and the circuit topology group based on the AC-AC three-level converter of a normal converter includes normal, push-and-pull, semi-bridge and full bridge topologies, which reduces voltage stress of power switch, series of power conversion and increases power factors of input side, conversion efficiency and power density.

An AC-AC Converter for an AC source which in one embodiment has a first rectifier section rectifying the AC source into a first pulsed DC link voltage signal and a high frequency modulating section coupled to the first pulsed DC link voltage signal and producing a high frequency AC voltage signal. A high frequency transformer is coupled to the high frequency AC voltage signal producing a transformed high frequency AC signal. There is a second rectifier section coupled to the transformed high frequency AC signal and producing a second pulsed DC voltage signal and an unfolder section coupled to the second pulsed DC voltage signal and producing an output AC signal.

A method of controlling an uninterruptible power supply apparatus (UPS) is provided. The UPS apparatus includes at least an AC input voltage, a DC input voltage and a single-phase AC / AC converter. The single-phase AC / AC converter includes an AC inductor, a bus capacitor, a boost arm, a common arm and a buck arm. The method includes steps of: controlling the bus voltage to have a DC component and full-wave rectifying component, and setting a bus voltage parameter K so that the bus voltage approaches to a full-wave rectifying voltage when K approaches to 1, wherein 0≦K≦1.

The invention provides a high-frequency isolation single-phase photovoltaic grid-connected system and a control method thereof. The high-frequency isolation single-phase photovoltaic grid-connected system consists of a photovoltaic array, a buffering capacitor, a high-frequency converter, a high-frequency transformer, an AC / AC converter, a filter and an electric power grid. A high-frequency chain-linked technology is utilized, so the electrical isolation between a photovoltaic power generation system and the electric power grid can be realized, the isolation transformer and the weight and the size of the entire system are reduced, only two-level power conversion is required, the topology is simplified, and the reliability of the entire system and the electric power transformation efficiency are improved. In addition, aiming at the characteristics of the topology and the photovoltaic system, an optimized control algorithm is proposed, so the unfavorable influence of the system from the fluctuation of the voltage outputted by the photovoltaic array can be overcome, the high quality of the electric power outputted by the entire system can be ensured, the distortions is small, the dynamic reaction is fast, the energy can flow in two directions, and reactive compensation can be supplied according to the requirement of the electric power grid.

The present invention relates to a wind turbine facility comprising a power generator operationally connected to an AC / AC converter adapted to receive variable frequency AC-power from the power generator, and adapted to generate substantially fixed frequency AC-power. The wind turbine facility further comprises a harmonic filter system, and a grid transformer comprising a primary winding being operationally connected to the AC / AC converter, and a secondary winding adapted to be operationally connected to an associated, substantially fixed frequency AC-power supply grid. The grid transformer further comprises a tertiary winding being operationally connected to the harmonic filter in order to suppress unwanted harmonics, such as selected harmonics generated by the AC / AC converter. The turn ratio between the primary and tertiary windings is selected in such a manner that a voltage of the tertiary winding is lower than a nominal voltage level of the associated AC-power supply grid voltage.

This invention relates to a boost high frequency AC / AC converter, which circuit is cascaded by an energy storage inductor, an input cycle converter, a HF transformer, an output cycle converter and an input and output filter circuit to turn a bad unstable AC current to a stable shared high grade sine AC current having the advantages of high frequency electric isolation, simple topological circuit, two stages of power transformation, two-way power-flow, high power factor at the supply side.

The invention discloses a Cuk-converter-based high-frequency isolated three-level AC-AC converter. In the converter, two coupling capacitors in a non-isolated Cuk three-level topology are both divided into two parts between which a serial isolated transformer is inserted; the middle connecting points of the primary sides of the two transformers are connected with the middle points of two bidirectional power switch tubes on the left side and the middle points of the two bidirectional power switch tubes on the right side respectively; and a power supply end and an output end form a circuit topological structure capable of converting an unstable high-voltage current into a stable or adjustable common-frequency sinusoidal alternating current by combining an input filter and an output filter respectively. In the invention, the power conversion stage number is small, fewer power switch elements are used, a bidirectional power current can be realized, the converter has an electrical isolation property, the spectral characteristic of the front end voltage of the output filter is desirable, the conversion efficiency and power density are improved, a voltage regulation range is wide, voltage boosting and reducing regulation can be realized, and the volume and weight of the output filter can be realized.

Active AC snubbers for AC / AC converters are provided. The active snubbers are actively-controlled AC snubbers that may be used in AC / AC power converters including direct AC converters. The active snubbers provide a free-wheeling path for AC / AC converters, ensuring that the converters are tolerant of errors in measurements and timings and of faults. The desired safe commutation of the switching devices when accurate measurements of voltage and current polarities become difficult or under fault contingencies when trapped energy needs to be dispatched safely is ensured. In addition, the active AC snubber may provide equal voltage sharing among the series-connected devices and clamp output voltages.

The invention discloses a power electronic transformer based on an energy injection type direct AC-AC converter. The power electronic transformer comprises a high-frequency transformer, a primary AC-AC converter topology module and a secondary AC-AC converter topology module. The primary AC-AC converter topology module and the secondary AC-AC converter topology module are in a symmetrical topology structure. The primary topology module is connected with the primary side of the high-frequency transformer. The secondary topology module is connected with the secondary side of the high-frequency transformer. According to the power electronic transformer, single-stage conversion and bidirectional transmission of the energy can be realized, the topology structure is simple, the conversion efficiency is high, the size is small, and the cost is low.

The invention provides a three-phase traction electricity supplying system, and relates to the field of urban rail and trunk line railway traction electricity supplying. The secondary edge of a main substation feeds out a three-phase cable; the three-phase cable is parallel to a three-phase traction net; a traction transformer Ti adopts Y / d wiring, the original edge is connected with the three-phase cable, and the secondary edge is connected with the three-phase traction net; the three-phase traction net is composed of a first electricity supplying rail, a second electricity supplying rail anda steel rail which are insulated with one another; the traction transformer Ti adopts the Y / d wiring, the original edge Y wiring of the traction transformer is connected into ABC with the same phase,and three terminals of the secondary edge d wiring of the traction transformer are connected with the first electricity supplying rail, the second electricity supplying rail and the steel rail correspondingly; and a vehicle-mounted electricity supplying system is composed of a vehicle-mounted cable and a three-phase AC-DC-AC convertor, a first single core cable, a second single core cable and a ground wire of the vehicle-mounted cable make contact with the first electricity supplying rail for being energized through an electricity brush, the second single core cable makes contact with the second electricity supply rail for being energized through an electricity brush, the ground wire makes contact with the steel rail for being energized through an electricity brush, and electricity is supplied to the three-phase AC-DC-AC convertor and a three-phase motor.

An AC-AC converter configured of a forward converter that converts alternating current to direct current and a reverse converter that converts direct current to alternating current, wherein a first semiconductor switch series circuit, a second semiconductor switch series circuit, and a capacitor series circuit are connected in parallel, a first inductor is connected between one end of an alternating current input and a series connection point of the first semiconductor switch series circuit, a bidirectional switch is connected between the one end of the alternating current input and a series connection point of the second semiconductor switch series circuit, a second inductor is connected between the series connection point of the second semiconductor switch series circuit and one end of an alternating current output, and a series connection point of the capacitor series circuit is connected to the other end of the alternating current input and the other end of the alternating current output. Because of this, it is possible to keep the inductor loss of the rectifier sufficiently small when input voltage is within a specified range. Also, in addition to this, it is possible to reduce switching loss more than in heretofore known circuits when carrying out a compensation action.

This invention discloses a Zeta three-level AC-AC converter, which converts a DC Zeta topological single-way switch tube to a dual-way switch tube, adds a supply level mode branch and a dual switch tube isoalting it and adds a zero-level mode dual-switch tube in front of the output filter combined with a non-complementary control strategy, and input and output filters are added to the supply and output ends to make up of a circuir topological structure of stable and adjustable same frequency and high quality sine AC circuit, the power conversion series of this invention is less and dual power flow can be realized, the voltage spectrum character in front of the output filter is good, conversion efficiency and power density are increased, the step regulation can be realized and the volume and weight of the output filter can be reduced and the output waveform quality is increased.

A circuit device is provided for driving an AC electric load, of the type inserted between a terminal of an AC power supply line and a terminal of the electric load to be driven and including a generator of PWM signals to be transferred to the load. This circuit is an AC / AC converter adapted to power supply the load from any level of the power supply line sinusoid and comprising first and second voltage driven switches, the first switch to power supply the load and the second switch to enable loop-back of the current. The switches always operate in a complementary manner, i.e., when the first switch is on, the other is off, and vice versa.

The invention discloses a cascaded flexible AC (alternating-current) link converter topological structure which comprises a three-phase AC power supply, three power regulation units, three Buck type direct AC-AC converters UT-AC, a three-phase multi-winding isolation transformer and three LC low-pass filters, wherein each power regulation unit is formed by two bipolar direct type AC-AC convertersBT-AC. According to the topological structure of the invention, the power flow between interconnected feeder lines can be controlled, the power restoration of an isolated load can be realized under the condition of a flexible interconnection fault of feeder lines in a power distribution network, the permeability of distributed power generation in a power distribution network can be improved through the flexible interconnection of the feeder lines in the power distribution network, and the electric energy quality and the power supply reliability of the power distribution network are improved.

Power flow controllers based on Imputed DC Link (IDCL) cells are provided. The IDCL cell is a self-contained power electronic building block (PEBB). The IDCL cell may be stacked in series and parallel to achieve power flow control at higher voltage and current levels. Each IDCL cell may comprise a gate drive, a voltage sharing module, and a thermal management component in order to facilitate easy integration of the cell into a variety of applications. By providing direct AC conversion, the IDCL cell based AC / AC converters reduce device count, eliminate the use of electrolytic capacitors that have life and reliability issues, and improve system efficiency compared with similarly rated back-to-back inverter system.

The invention discloses a power converter and an input / output frequency conversion method. The power converter comprises a first-stage AC / AC converter, a transformer, a second-stage AC / AC converter and an LC filter, wherein the first-stage AC / AC converter rectifies three-phase alternating current from a power grid, and carries out high-frequency chopping on the rectified waveform according to theprinciple that volt-second products of all pulses are equal, thereby generating a high-frequency pulse sequence; the transformer isolates the high-frequency pulse sequence generated by the first-stage AC / AC converter and outputs to the second-stage AC / AC converter; the second-stage AC / AC converter converts the high-frequency pulse sequence output by the transformer into a pulse sequence fundamental wave frequency of which is the required output frequency; and the LC filter filters the pulse sequence output by the second-stage AC / AC converter to obtain alternating current with the required output frequency. The power converter eliminates the direct current state in the power conversion process, and can complete the input / output frequency conversion process by using two stages of converters, thereby greatly enhancing the frequency conversion efficiency.

The invention discloses an AC / AC converter. A corresponding principle comprises: acquiring alternating current power Uin (AC) from power grid (L, N, grounding); sending to a high-frequency transformer T-2 after passing through an EMI filter which is formed by differential mode capacitors C1, C2, a common mode choke T-1 and common mode capacitors C3, C4; performing by turns high frequency conduction to primary switches S1, S2of the high-frequency transformer T-2. Then, a power frequency voltage added on primary windings N3, N4 of the high-frequency transformer T-2 is converted into a high frequency voltage so that secondary windings N5, N6 of the high-frequency transformer T-2 can get the corresponding high frequency voltage. Through correspondingly controlling the switches S3, S4 of the secondary windings, any alternating current voltage Uo (AC) which is common-frequency, same-phase or anti-phase with an input voltage can be acquired on an output terminal. Through carrying out filtering by using a low pass filter which is formed by a L1 and a C5, a distortion factor of the Uo (AC) can be reduced.

An AC-AC converter device includes first and second AC input terminals and first and second AC output terminals. An input device is connected between an input node, a common node, a positive DC terminal and a negative DC terminal, wherein the input node is connected to the first AC input terminal via a first input inductor. An output device is connected between an output node, the positive DC terminal and the negative DC terminal, wherein the output node is connected to the first AC output terminal via an output inductor. A common device is connected between the common node, the positive DC terminal and the negative DC terminal, where the common node is connected to the second AC input terminal via a common inductor. A control device is provided for controlling the switches of the output device and the common device.

A control apparatus for an AC-AC direct converter. The control apparatus includes a calculator providing a phase command θ* of an output voltage of the converter, a calculator providing a q-axis current iq by using output currents iu and iw and the phase command θ*, a detector detecting a pulsation component contained in the q-axis current iq, a calculator providing a phase correction magnitude θcmp so as to decrease the pulsation component, and an adder / subtractor correcting the phase command θ* by using the correction magnitude θcmp. This apparatus can decrease the output voltage distortion and low frequency torque pulsation and can suppress the increase of an output current without weakening a magnetic flux, even when the converter is operated in an overmodulation region.

The invention discloses a single-phase bipolar AC-AC converter topological structure. The single-phase bipolar AC-AC converter topological structure comprises single-phase system alternating current power supply, a power conversion unit, an LC low-pass filter, a load part and a signal control unit. The output end of the single-phase system alternating current power supply is connected with the input end of the power conversion unit, the power conversion unit includes a positive polarity bridge arm and a negative polarity bridge arm, the output end A of the positive polarity bridge arm and theoutput end B of the negative polarity bridge arm are connected to the input end of the LC low-pass filter, and the output end of the LC low-pass filter is connected to the load part. The topological structure solves the problem of commutation in an existing AC-AC converter topological structure and the problem of only being able to output unipolar voltage or bipolar voltage with narrow range, a PWM modulation strategy is used, only two switching tubes perform opening and closing actions in each switching cycle, the total switching loss is effectively reduced, and the efficiency of the converter is improved.