164results about "Ac-ac conversion" patented technology

The utility model belongs to the technical field of electronic circuit, especially relates to a passive low harmonic frequency converter special for rail transit air conditioner. The frequency converter includes: passive filter module, rectifier module, precharge module, voltage-sharing filter module, inverter module and control module. The input end of passive filter module is connected to the output end of alternating -current source, and the output end is connected to the input end of rectifier module, and the output end of rectifier module is connected to the input end of precharge module, the output end of precharge module is connected to the input end of voltage-sharing filter module, the output end of voltage-sharing filter module is connected to the input end of inverter module, and the output end of inverter module is the voltage output end of passive low harmonic frequency converter special for rail transit air conditioner, and inverter module and control module are connected through inverter control and protection circuit. The utility model can reduce the harmonic interference of frequency converter inverter to input power grid, protects the electrical equipment on power grid, and improves the security of operation.

The application relates to a dual-motor control circuit, method and variable-frequency speed regulation system. A mode switching module is arranged, so that in the case of common bridge arm failure, the phase connected between the first motor, the second motor and the common bridge arm can be switched to be connected with the bus capacitor bridge arm, so that the inverter topology is converted from five bridge arms to four bridge arms. At this time, the variable-frequency speed regulation system can keep normal operation in the four-bridge-arm mode, and system shutdown caused by common bridge arm failure can be avoided.

An electronic circuit includes a rectifier module and an energy storage module. The rectifier module includes a three-phase rectifier bridge including first, second, and third bridge arms connected in parallel to each other, and a bidirectional switch assembly including first, second, and third bidirectional switches. One ends of the first, second, and third bidirectional switches are connected to midpoints of the first, second, and third bridge arms, respectively. The energy storage module is connected to a direct-current output end of the rectifier module and includes two capacitors connected in series to each other. One of the two capacitors is connected in parallel to a direct-current load. Other ends of the first, second, and third bidirectional switches are connected between the two capacitors.

The application provides a MOSFET-based conversion topology and an AC power commutation control method, wherein the conversion topology comprises at least four commutation modules connected to the positive and negative poles of the X phase and Y phase of the AC power respectively, the commutation module comprises at least two MOSFETs, one end of a MOSFET is connected to the AC power, the other end of the MOSFET is connected to one end of another MOSFET, the other end of the other MOSFET is an output, and the two MOSFETs are turned on and turned off simultaneously. The conversion topology uses MOSFET devices to perform commutation control on medium-high frequency voltage signals, can realize switching of voltage signals among multiple paths, and has small semiconductor device package, low cost and wide selection range.

Modified control scheme for a single-stage voltage converter for voltage conversion between a single-phase AC network and a DC network. This scheme involves splitting each pulse into multiple sub-pulses when using pulse-width modulated control of a full-bridge circuit. This reduces the RMS current in the leakage inductance of the voltage converter's transformer.

Provides a highly reliable power conversion device, etc. A power conversion device (100) includes: a conversion circuit (10), a smoothing capacitor (20), an inverter circuit (50), an inverter control circuit (61), and an overvoltage protection circuit (40), and also includes: an overvoltage protection control circuit (62) which performs overvoltage protection control to switch the switching element (41) to the on state when the DC voltage of the smoothing capacitor (20) reaches a specified value after the inverter circuit (50) stops. After the overvoltage protection control starts, the inverter control circuit (61) performs winding short-circuit control to turn on one of the upper and lower arms of the inverter circuit (50) in all phases and turn off the other arm in all phases. The winding short-circuit control starts according to a specified state quantity, wherein the specified state quantity is correlated with the cumulative heat generation of the resistive element (42) generated by the overvoltage protection control.

Included are a rectifier circuit (210) that rectifies a first alternating-current voltage; a reactor (220) connected to the rectifier circuit (210); a capacitor (230) connected to an output end of the rectifier circuit (210); an inverter (240) that is connected to the capacitor (230), generates a second alternating-current voltage through operations of a plurality of switching elements (241 to 246), and applies the second alternating-current voltage to a motor (310) including a stator and a rotor; and a control unit (270) that performs operation controls on the plurality of switching elements (241 to 246). The control unit (270) causes the inverter (240) to apply, to the motor (310), the second alternating-current voltage having a higher frequency than when the motor (310) is in compression operation so as not to rotate the rotor. The application of the high-frequency second alternating-current voltage from the inverter (240) to the motor (310) generates a regenerative current and a current flows to the capacitor (230) due to the regenerative current without impairing the capacitor (230).

A hybrid transformer apparatus and a control method thereof are provided. The hybrid transformer apparatus includes at least one power electronic module having a parallel converter and a series converter electrically connected to form a hybrid converter. The parallel converter is electrically connected to the low voltage side of a distribution transformer. A controller controls the signals of the parallel converter and the series converter, including switching switches, a bypass circuit, and a compensation transformer. The controller reduces load voltage variation in response to changes in input voltage. A communication device transmits voltage and current information to the controller. The hybrid transformer apparatus also includes a circuit breaker and a bypass circuit.

A load control device for controlling the amount of power delivered from an AC power source to an electrical load is operable to conduct enough current through a thyristor of a connected dimmer switch to exceed rated latching and holding currents of the thyristor. The load control device comprises a controllable-load circuit operable to conduct a controllable-load current through the thyristor of the dimmer switch. The load control device disables the controllable-load circuit when the phase-control voltage received from the dimmer switch is a reverse phase-control waveform. When the phase-control voltage received from the dimmer switch is a forward phase-control waveform, the load control device is operable to decrease the magnitude of the controllable-load current so as to conduct only enough current as is required in order to exceed rated latching and holding currents of the thyristor.

A power conversion device (10) comprising: a first power conversion unit (5) that converts the DC voltage applied by a first and a second capacitor unit (40, 42) into three-phase AC voltage; a second power conversion unit (6) that converts single-phase AC voltage or three-phase AC voltage into DC voltage and applies the DC voltage to the first and the second capacitor units (40, 42); a first parallel flat conductor (30) having three plate-shaped conductors to which high potential, medium potential and low potential from the first capacitor unit (40) are applied; a second parallel flat conductor (32) having three plate-shaped conductors to which high potential, medium potential and low potential from the second capacitor unit (42) are applied;and a third parallel flat conductor (34) arranged on a side opposite the first and second capacitor units (40, 42) with respect to the first and second parallel flat conductors (30, 32).

It refers to a motor driver and a method for using the motor driver. The motor driver includes: a motor driver main body (1) with a control unit (CU), electrically connected with a power supply system (2); characterized in that, further comprising: a grounding circuit (GC), electrically connected with DC bus negative pole (DCN) of the motor driver main body (1), and includes a sampling resistance (R1); a sampling circuit (AD) including two sampling ends and an output end, and the two sampling ends are electrically connected at both ends of the sampling resistance (R1) to collect a voltage on the sampling resistance (R1), the output end is electrically connected with the control unit (CU) to provide collected voltage on the sampling resistance (R1) to the control unit (CU); the control unit (R1) is configured to determine grounding type of the power supply system (2) according to the collected voltage on the sampling resistance (R1). The technical solutions can identify the grounding type of the power supply system (2).

A power electronic transformer includes three modules, the three modules each including: a first submodule; a second submodule; and a third submodule including a first power conversion module including N first power conversion units having input ports connected to the N output ports of the first submodule in one-to-one correspondence, and a second power conversion module including M first power conversion units having input ports connected to the M output ports of the second submodule in one-to-one correspondence, the first input port of the first submodule of the three modules has one terminal connected to three phases of a first three-phase alternating current in one-to-one correspondence, and the other terminal connected to three phases of a second three-phase alternating current in one-to-one correspondence, output ports of the N first power conversion units are connected in parallel to output ports of the M first power conversion units.

The application relates to a voltage compensation control device and relates to the technical field of power electronics. The device comprises an energy storage module for storing electric energy; a full-bridge module comprising a direct-current side, an alternating-current side input end and an alternating-current side output end, the direct-current side being connected with the energy storage module; a switching module arranged on a first path between the alternating-current side input end and a first phase line of a power grid, on a second path between the alternating-current side input end and a second phase line of the power grid and on a third path between the alternating-current side output end and the first phase line, and used for selecting the conduction of the first path, the second path and the third path respectively; a control module connected with the switching module and the full-bridge module respectively, and used for controlling the switching module and the full-bridge module to work in a full-bridge rectification mode when the power grid is in a normal working condition; and controlling the switching module and the full-bridge module to work in an alternating-current alternating-current conversion mode when the first phase line meets a voltage compensation condition. The method can realize the efficient reuse of power switching devices.

A power conversion device includes a plurality of power modules; a plurality of smoothing capacitors; a first DC bus bar; and a second DC bus bar. The first and second DC bus bars include positive and negative electrode bus bars laminated on each other. The plurality of Smoothing capacitors are disposed between the first DC bus bar and the power module. The first DC bus bar includes a protrusion portion that passes between the plurality of smoothing capacitors and extends to a disposition side of the power module, and a first connection portion connected to the smoothing capacitor. The protrusion portion includes a second connection portion connected to the second DC bus bar. The second DC bus bar includes a third connection portion connected to the power module and a fourth connection portion connected to the second connection portion.

A power conversion system includes a plurality of submodules for respective arms, the plurality of submodules being provided between respective phases of first and second AC power systems and DC buses, and cascade-connected to each other. Each of the plurality of submodules serves as a unit converter that converts between AC power and DC power. The power conversion system further includes reactors connected between the plurality of submodules for respective arms and portions for connection to the AC power systems, and at least one housing chamber. The plurality of submodules for respective arms and the DC buses are housed in the at least one housing chamber, and the reactors are arranged outside the housing chamber.

The application discloses a converter fault ride-through control method based on circulating current compensation and negative sequence current injection, and belongs to the technical field of electric power control; the method comprises the following steps: collecting M3C bridge arm voltage and current in real time; performing positive and negative sequence decomposition on the collected voltage and current, and converting to the dq synchronous rotating coordinate system; calculating the imbalance power between the bridge arms according to each component of the voltage and current; calculating the required negative sequence current injection amount and circulating current injection amount according to the set power balance proportion coefficient and the imbalance power between the bridge arms, and converting the required negative sequence current injection amount and circulating current injection amount into voltage reference values; and generating a driving signal through nearest level approximation modulation. When an asymmetric fault occurs in a line, in order to balance the asymmetric voltage between each bridge arm in the M3C, the method realizes the M3C fault ride-through by injecting negative sequence current into the fault line and injecting circulating current between the converters, thereby reducing the control difficulty of the circulating current path, reserving part of the negative sequence current characteristics for line fault detection, and realizing the comprehensive optimization of the internal and external characteristics of the M3C during the fault.

A device includes an alternating current (AC) to direct current (DC) converter configured to convert a single-phase AC power signal to a DC power signal. The device may also include a DC to AC converter having an input electrically coupled to the AC to DC converter and configured to receive the DC power signal and having and one or more inverters coupled to the input and configured to change the DC power signal to a multi-phase power supply having at least four AC power signals that are phase-shifted relative to each other.

The application discloses a control method, device and system of a matrix converter without an electrolytic capacitor and a medium, wherein the matrix converter without the electrolytic capacitor comprises a rectifying unit, an inverting unit and an electrolytic capacitor, the method comprises the following steps: obtaining a phase-locked angle, and obtaining an auxiliary control current and a direct control current according to the phase-locked angle; obtaining a bus voltage reference value according to the auxiliary control current; obtaining a current amplitude reference value according to the bus voltage reference value; obtaining a direct control current reference value according to the current amplitude reference value, and realizing direct control line current sinusoidal through PIR control according to the direct control current and the direct control current reference value. Thus, the bus voltage reference value is obtained through closed-loop regulation, and then the current amplitude reference value is effectively calculated, so that input and output power matching is realized, and the adaptability requirement of different loads is met.

The expression (1) below holds, where Vmax (V) represents a maximum input voltage value of a power converter (100), La (µH) represents an inductance of AC reactors (13), Vp (V) represents a withstand voltage of switching elements (Sr1, Sr2, Ss1, Ss2, St1, St2), and Cf (µF) represents capacitive components (15) between phases. The power converter (100) includes: a current limiting circuit (16) including two main circuit relays (16a) for two of three-phase electric paths between a three-phase AC power supply (2) and a converter unit (11), and a current limiting element (16b) connected in parallel to at least one of the two main circuit relays (16a). La<Vp / √2*Vmax−1 / 1.15+Cf*1.33−5 / 3

The present invention relates to a device and a method for diagnosing a failure of an inverter initial charging circuit. The device for diagnosing a failure of an initial charging circuit according to the present invention is advantageous as follows: it is possible to detect whether a relay of the initial charging circuit is malfunctioning or not by using a photocoupler connected in parallel with an initial charging resistor of the initial charging circuit, on the basis that, if a current flows through the initial charging resistor in a relay-on state, the photocoupler is turned on; and it is possible to prevent component failure or burnout from occurring due to a high current flowing through the initial charging resistor in the case of a relay failure.

The application discloses a kind of electrolytic capacitor matrix converter and active damping control method, device and medium, wherein electrolytic capacitor matrix converter includes rectification unit, inverter unit and parallel electrolytic capacitor between rectification unit and inverter unit, method includes: obtaining inverter d-axis current, inverter q-axis current and motor rotor speed, and according to inverter d-axis current, inverter q-axis current and motor rotor speed, obtain d-axis modulation voltage and q-axis modulation voltage;Bus voltage is obtained, and according to the high-frequency component of bus voltage and damping coefficient, active damping control voltage is obtained;According to d-axis modulation voltage, q-axis modulation voltage and active damping control voltage, motor is carried out SPWM control. Therefore, by active damping control in electrolytic capacitor virtual parallel harmonic resistance, to effectively reduce bus voltage high-frequency ripple, so as to ensure the reliability and stability of electrolytic capacitor matrix converter.

A circuit, particularly suitable for driving a motor of a vacuum pump 220, comprises a filter 212 to receive an alternating current (AC) electrical input power and supply a filtered AC electrical powe

An electronic device and a variable frequency control system using the electronic device. The electronic device may comprise: a shielding layer, which is inserted between a current outflow terminal of a switching device and a grounding conductor; and a conductive elastomer, which is used for connecting the current outflow terminal to the shielding layer.