A conversion device includes: an inductor connected to the AC power grid; a first-stage converter configured to output a bus voltage based on the AC power grid; a second-stage converter configured to convert the bus voltage into an output voltage to the load; and a filtering network, wherein a first resistance-capacitance circuit is disposed between the first and third terminals of the filtering network, a second resistance-capacitance circuit is disposed between the second and third terminals of the filtering network, the first terminal of the filtering network is connected to the AC power grid, the second terminal of the filtering network is connected to the bus or the second terminal of the second-stage converter, and the third terminal of the filtering network is grounded through a first capacitor.

The invention provides a power converter for converting a three-phase alternating current (AC) supply to a direct current (DC) output, the power converter comprising: a first selector configured to select one of the highest, the second highest or the lowest instantaneous phase to phase voltages of the three-phase supply to provide a first power rail; a second selector configured to select a different one of the highest, the second highest or the lowest instantaneous phase to phase voltages of the three-phase supply to provide a second power rail; a first transformer coupled to the first power rail; a second transformer coupled to the second power rail; a combiner configured to combine the outputs of the first and second transformers to provide the DC output; and a duty cycle controller configured to vary duty cycles of the first and/or second transformers to thereby vary the relative contributions of the first and second power rails to the DC output.

Provided is a parallel inverter device with which, among inverter devices each including a DC/AC inverter and the like, control of a parallel operation accompanied with an increase in power capacity or the like can be easily performed without using a control line for connecting between the inverter devices. A parallel inverter device (1) includes a switcher (15) in which, on an output line to which a load (40) is connected, two MOSFETs connected in series to the load are arranged so as to face each other so that their energization directions are opposite directions. ON/OFF of each MOSFET of the switcher (15) is controlled based on a polarity of an AC voltage output from a filter circuit (10) of the parallel inverter device (1) and a direction of a current flowing to the load (40) on the output line so that a cross current is interrupted. Further, a voltage difference or a phase difference between a load voltage and the AC voltage output from the filter circuit (10) is controlled so as to be reduced so that occurrence of the cross current is prevented.

Provided is a parallel inverter device with which, among inverter devices each including a DC/AC inverter and the like, control of a parallel operation accompanied with an increase in power capacity or the like can be easily performed without using a control line for connecting between the inverter devices. A parallel inverter device (1) includes a switcher (15) in which, on an output line to which a load (40) is connected, two MOSFETs connected in series to the load are arranged so as to face each other so that their energization directions are opposite directions. ON/OFF of each MOSFET of the switcher (15) is controlled based on a polarity of an AC voltage output from a filter circuit (10) of the parallel inverter device (1) and a direction of a current flowing to the load (40) on the output line so that a cross current is interrupted. Further, a voltage difference or a phase difference between a load voltage and the AC voltage output from the filter circuit (10) is controlled so as to be reduced so that occurrence of the cross current is prevented.

A power supply device includes: “m×n” switching elements; capacitors connected in series to corresponding ones of the switching elements and forming “m×n” series circuits; a charger charging the capacitors; “m” transformers in which primary windings are connected to both ends of corresponding ones of “m” parallel circuits formed by connecting “n” units of the series circuits in parallel to one another with the polarity aligned; a current detection unit detecting, as a detected current value, current flowing through a multistage series circuit in which secondary windings of the transformers are sequentially connected in series so that both ends of the circuit serve as output terminals; a control unit outputting a command signal generated based on the detected current value and a current command being a target value of the current output from the output terminals; and a drive unit driving the switching elements and the charger based on the command signal.

A power supply device includes: “m×n” switching elements; capacitors connected in series to corresponding ones of the switching elements and forming “m×n” series circuits; a charger charging the capacitors; “m” transformers in which primary windings are connected to both ends of corresponding ones of “m” parallel circuits formed by connecting “n” units of the series circuits in parallel to one another with the polarity aligned; a current detection unit detecting, as a detected current value, current flowing through a multistage series circuit in which secondary windings of the transformers are sequentially connected in series so that both ends of the circuit serve as output terminals; a control unit outputting a command signal generated based on the detected current value and a current command being a target value of the current output from the output terminals; and a drive unit driving the switching elements and the charger based on the command signal.

A conversion device includes: an inductor electrically connected to the AC power grid; a first-stage converter configured to output a bus voltage according to the AC power grid, wherein the first-stage converter includes an N-level alternating current-direct current (AC-DC) converter, and the N-level AC-DC converter includes a plurality of switch bridge arms, wherein both an upper bridge arm and a lower bridge arm of each of the plurality of switch bridge arms of the N-level AC-DC converter include a plurality of semiconductor devices connected in series, and a rated withstand voltage Vsemi of each of the semiconductor devices is greater than or equal to (Vbus*δ)/((N−1)*Nseries*λ); and a second-stage converter configured to convert the bus voltage into an output voltage to supply energy to the load.

A power converter includes: plural inverter units connected in parallel to a DC power supply, including a storage battery, on a DC side and a DC fuse in each of current paths between the DC power supply and the inverter units, the DC fuse configured to, when a short-circuit failure occurs in any of the inverter units, be blown in the current path between the DC power supply and the inverter unit having the short-circuit failure. The number of the inverter units is a number with which a condition that, when the DC fuse between the DC power supply and the inverter unit having the short-circuit failure is blown, none of a plurality of the DC fuses between the DC power supply and a plurality of other inverter units that do not have the short-circuit failure are blown is satisfied.

A system comprises a first inverter and a second inverter connected in parallel, a coupled inductor connected to outputs of the first inverter and the second inverter, wherein the coupled inductor comprises a plurality of windings formed by a single winding wire and an output filter coupled to an output of the coupled inductor.

A system comprises a first inverter and a second inverter connected in parallel, a coupled inductor connected to outputs of the first inverter and the second inverter, wherein the coupled inductor comprises a plurality of windings formed by a single winding wire and an output filter coupled to an output of the coupled inductor.