Abstract: A power assist apparatus includes a branch power lines, a first power storage device, a power assist converter, and a second power storage device. The branch power line is connected to a main line of a natural energy power generation system, which is connected to a system. The first power storage device connected to the branch power line. The power assist converter connected to the branch power line. The second power storage device connected to a downstream side of the power assist converter.

Abstract: A DC boosting circuit includes switch connected to a first circuit and a second circuit. The first circuit includes first and second elements, and the second circuit includes the second element and a third element. The first and second elements store energy based on an input voltage when the switch is in a first state. The third element stores energy from the second element when the switch is in the second state. The second circuit outputs a voltage greater than the input voltage, and the first, second, and third elements are reactors or capacitors.

Abstract: A snubber circuit includes a current-variation suppressor, a voltage-variation suppressor, a retrieving circuit, and a discharging circuit. The current-variation suppressor is connected between a bridge circuit and a power supply and reduces current variation when switches in the bridge circuit are controlled. The voltage-variation suppressor is parallel to the switches and reduces voltage variation when the switches are controlled. The retrieving circuit transfers energy stored in the current-variation suppressor when the switches are controlled to the voltage-variation suppressor. The discharging circuit discharges energy stored in the voltage-variation suppressor when the switches are controlled to an AC side of the bridge circuit when the semiconductor switches are controlled.

Abstract: In some aspects, a direct current power source, formed of a series connection circuit of single power sources, which has three mutually different voltage levels including zero can be provided with first, second, third, and fourth arm pairs, each configured by connecting two arms formed of semiconductor switches in series, an alternating current switch configured by combining semiconductor switches. As such, a plurality of voltage levels can be to be selected from and output by an on and off control of these switch elements.

Abstract: A DC boosting circuit includes switch connected to a first circuit and a second circuit. The first circuit includes first and second elements, and the second circuit includes the second element and a third element. The first and second elements store energy based on an input voltage when the switch is in a first state. The third element stores energy from the second element when the switch is in the second state. The second circuit outputs a voltage greater than the input voltage, and the first, second, and third elements are reactors or capacitors.

Abstract: A snubber circuit includes a current-variation suppressor, a voltage-variation suppressor, a retrieving circuit, and a discharging circuit. The current-variation suppressor is connected between a bridge circuit and a power supply and reduces current variation when switches in the bridge circuit are controlled. The voltage-variation suppressor is parallel to the switches and reduces voltage variation when the switches are controlled. The retrieving circuit transfers energy stored in the current-variation suppressor when the switches are controlled to the voltage-variation suppressor. The discharging circuit discharges energy stored in the voltage-variation suppressor when the switches are controlled to an AC side of the bridge circuit when the semiconductor switches are controlled.

Abstract: A series-parallel conversion device includes n cell series connection units and a plurality of inter-unit connection switches. Each connection unit has n?1 cells and one intra-unit switch. The connection switches connect adjacent connection units. The connection units are disposed in parallel in n columns between a positive electrode terminal and a negative electrode terminal. The intra-unit switch in a cell series connection unit column has a first terminal and a second terminal. The first terminal is connected to a negative electrode terminal of a k-th cell from the negative electrode terminal or the positive electrode terminal. The second terminal is connected to a positive electrode terminal of a (k?1)-th cell from the negative electrode terminal or the negative electrode terminal. The connection switch is connected between the first terminal of the intra-unit switch of the k-th column and a second terminal of an intra-unit switch of a (k+1)-th column.

Abstract: A power assist apparatus includes a branch power lines, a first power storage device, a power assist converter, and a second power storage device. The branch power line is connected to a main line of a natural energy power generation system, which is connected to a system. The first power storage device connected to the branch power line. The power assist converter connected to the branch power line. The second power storage device connected to a downstream side of the power assist converter.

Abstract: Aspects of the invention are directed to a multilevel power converter the includes a DC power supply assembly having a positive terminal, a negative terminal, and a zero terminal; a first semiconductor switch series circuit composed of first through sixth semiconductor switches connected in series between the positive terminal and the negative terminal. The converter can include a second semiconductor switch series circuit composed of a first bidirectional switch, seventh and eighth semiconductor switches, and a second bidirectional switch connected in series between the connection point of the first and second semiconductor switches and the connection point of the fifth and sixth semiconductor switches, a first capacitor connected in parallel with a series circuit of the third and fourth semiconductor switches and a second capacitor connected in parallel with the second semiconductor switch series circuit.

Abstract: In some aspects of the invention, a power semiconductor module is applied to a multi-level converter circuit with three or more levels of voltage waveform. A first IGBT, a diode whose cathode is connected to the emitter of the first IGBT, and a second IGBT having reverse blocking voltage whose emitter is connected to the emitter of the first IGBT, are housed in one package, and each of the collector of the first IGBT, the collector of the second IGBT, the connection point of the emitter of the first IGBT and the emitter of the second IGBT, and the anode of the diode, is an external terminal.

Abstract: In some aspects of the invention, a number of semiconductor switches through which output current passes can be reduced between a direct current power source side, which is an input, and an alternating current output, thus achieving loss reduction, and enabling higher efficiency, price reduction, and miniaturization of a device. In some aspects, a direct current power source, formed of a series connection circuit of single power sources, which has three mutually different voltage levels including zero can be provided with first, second, third, and fourth arm pairs, each configured by connecting two arms formed of semiconductor switches in series, an alternating current switch configured by combining semiconductor switches. As such, a plurality of voltage levels can be to be selected from and output by an on and off control of these switch elements.

Abstract: Aspects of the invention are directed to a multilevel power converter the includes a DC power supply assembly having a positive terminal, a negative terminal, and a zero terminal; a first semiconductor switch series circuit composed of first through sixth semiconductor switches connected in series between the positive terminal and the negative terminal. The converter can include a second semiconductor switch series circuit composed of a first bidirectional switch, seventh and eighth semiconductor switches, and a second bidirectional switch connected in series between the connection point of the first and second semiconductor switches and the connection point of the fifth and sixth semiconductor switches, a first capacitor connected in parallel with a series circuit of the third and fourth semiconductor switches and a second capacitor connected in parallel with the second semiconductor switch series circuit.

Abstract: In aspects of the invention, first and second series circuits of switching devices and a series circuit of capacitors are connected in parallel. Between the connection point in the first series circuit of switching devices and the connection point in the series circuit of capacitors, a first bidirectional switch is connected and, between the connection point in the second series circuit of switching devices and the connection point in the series circuit of capacitors, a second bidirectional switch is connected. The connection point in the first series circuit of switching devices is connected through a reactor to an input-output common connection line connected to one end of an AC power supply and the other end of the AC power supply is connected to the connection point in the series circuit of capacitors.

Abstract: In some aspects of the invention, a power semiconductor module is applied to a multi-level converter circuit with three or more levels of voltage waveform. A first IGBT, a diode whose cathode is connected to the emitter of the first IGBT, and a second IGBT having reverse blocking voltage whose emitter is connected to the emitter of the first IGBT, are housed in one package, and each of the collector of the first IGBT, the collector of the second IGBT, the connection point of the emitter of the first IGBT and the emitter of the second IGBT, and the anode of the diode, is an external terminal.

Abstract: An AC current source circuit converts a DC input voltage into an AC output current, and comprises a chopper circuit for converting a DC input voltage into a chopper voltage; and an inverter for converting the chopper voltage into an output AC current of a predetermined frequency. The inverter comprises at least four switch elements, and clamp-type snubber circuits corresponding to each of the switch elements are provided. The snubber circuit releases electric charges to the input terminal of the DC input voltage of the chopper circuit. The chopper circuit is connected to the inverter through a DC reactor. The DC input voltage is converted into a DC current by the chopper circuit and the DC reactor and transmitted to the inverter.