Abstract: Three or more circuits, in which series-connected low-voltage and high-voltage side switches including MOSFETs including parasitic diodes are connected across positive and negative terminals of each of smoothing capacitors, are connected in series. One of elementary series circuits, each including a capacitor and an inductor, is disposed between any adjacent two of the circuits with the elementary series circuits set to have the same period of resonance. The MOSFETs of rectifier circuits are brought into an ON state simultaneously with the MOSFETs of a driving inverter circuit and brought into an OFF state earlier than the MOSFETs of the driving inverter circuit by a period of time not exceeding a time period equal to (period of resonance)/2. A resonance phenomenon of the capacitor and the inductor is used and conduction loss in the rectifier circuits is reduced in DC/DC power conversion performed through charging and discharging operation of the capacitor.

Abstract: Three or more circuits including a driving inverter circuit and rectifier circuits are connected in series, each of the circuits including a high-voltage side MOSFET and a low-voltage side MOSFET connected in series as well as a smoothing capacitor having positive and negative terminals between which the MOSFETs are connected. LC series circuits, each including a capacitor and an inductor, are disposed individually between one specific circuit and the other circuits with periods of resonance of the LC series circuits made equal to one another. In performing DC/DC power conversion through charging and discharging operation of the capacitors, a resonance phenomenon of the LC series circuits is used to improve conversion efficiency and achieve a reduction in size of the apparatus structure.

Abstract: An uninterrupted power supply unit is provided with a straightforward switch connected between a power source and a load to supply or interrupt a power to a system. The combination of the outputs from two kinds of single phase inverters enables compensating for a variation in the system voltage in the normal condition and to supply a predetermined voltage to the load after decreasing in the system voltage and opening of a straight forward switch.

Abstract: In a power conversion apparatus that converts AC power to DC power, an inverter circuit including one or more single-phase inverters connected in series with each other is connected in series at the subsequent stage of a rectification of an AC input. At the subsequent stage of the inverter circuit, a smoothing capacitor connected via a rectification diode, and a short-circuiting switch for bypassing the smoothing capacitor are provided. The short-circuiting switch is subjected to ON/OFF control by PWM control such that a voltage of the DC voltage supply of the inverter circuit follows a target voltage. The inverter circuit is subjected to output control such that a DC voltage of the smoothing capacitor follows a target voltage and an input power factor is improved.

Abstract: A neutral point clamped three-phase three-level inverter is connected to a first DC power supply and single-phase inverters are connected in series with AC output lines of individual phases of the three-phase three-level inverter such that sums of output voltages of the three-phase three-level inverter and output voltages of the respective single-phase inverters are output to a load through a smoothing filter. An output control unit controls the three-phase three-level inverter so that the individual phases of the three-phase three-level inverter output primary voltage pulses at a rate of one pulse per half cycle and controls the individual single-phase inverters by PWM, so that output voltages to the individual phases of the load form sine waves of which phases are offset by 2?/3 from one phase to another, the sine waves having the same peak value.

Abstract: A power supply apparatus includes: an AC generator including an AC generating section, and a rectifier for rectifying an AC voltage generated in the AC generating section, and outputting a DC voltage; and a DC/DC converter for converting the output voltage of the rectifier into a DC voltage having a different voltage value, wherein the output voltage of the rectifier is set to be larger than the output voltage of the DC/DC converter in accordance with the rotation speed of the AC generating section and the amount of power supply to an electrical load connected to the DC/DC converter, and is stepped down and outputted by using the DC/DC converter. The power supply apparatus is capable of increasing an output power efficiently.

Abstract: An uninterrupted power supply unit is provided with a straightforward switch connected between a power source and a load to supply or interrupt a power to a system. The combination of the outputs from two kinds of single phase inverters enables compensating for a variation in the system voltage in the normal condition and to supply a predetermined voltage to the load after decreasing in the system voltage and opening of a straight forward switch.

Abstract: The present invention provides a power device including a converter part (2) for converting an AC voltage to a DC voltage; an inverter part (3) for converting the DC voltage outputted from the converter part (2) to the AC voltage; and a transformer (4) having an inductance forming a series resonance circuit together with an electrostatic capacity of a load (20) to boost the AC voltage outputted from the inverter part (3). In the power device, an inductance (7) is connected to the output part of the inverter part (3) in parallel with the transformer (4). Thus, in a discharge part 6 provided in the load (20), since when a discharge is not generated, a recovery current is not supplied to a circulating current diode in the inverter part (3), or the quantity of the recovery current is reduced, the heat generation of the circulating current diode can be suppressed without increasing the number of elements of the circulating current diode.

Abstract: A power converting apparatus is provided with three sets of half-bridge inverters (4a-4c) connected between output terminals of a solar battery (1), each of the half-bridge inverters (4a-4c) including two series-connected switching devices, single-phase inverters (5a-5c) connected to individual AC output lines of the bridge inverters (4a-4c), and two series-connected capacitors (6a, 6b) for dividing a voltage of the solar battery (1), wherein output terminals of the single-phase inverters (5a-5c) are connected to individual phases of a three-phase power system (2). Each of the half-bridge inverters (4a-4c) is operated to output one pulse per half cycle, each of the single-phase inverters (5a-5c) is controlled by PWM control operation to make up for a voltage insufficiency from the system voltage, and sums of outputs of the half-bridge inverters (4a-4c) and the single-phase inverters (5a-5c) are output to the power system (2).

Abstract: In a power conversion device which performs DC/DC conversion, an inverter circuit (20), which is formed of one or more single-phase inverters (20a) and (20b) connected in series to each other, is connected in series to a DC power supply (1) in its subsequent stage. In further subsequent stage, a smoothing capacitor (6) connected to the inverter circuit (20) via a rectifier diode (5), and a shorting switch (4) which bypasses the smoothing capacitor (6) are provided. The shorting switch (4) is switched ON to charge capacitors (25) and (35) included in the single-phase inverter (20a) and (20b), respectively, whereas the shorting switch (4) is switched OFF to discharge the capacitors (25) and (35), whereby the voltage of the smoothing capacitor (6) is controlled.

Abstract: An electric discharge machining apparatus includes: electrodes the total quantity of which is equal to N; an alternating-current power source; and capacitors the total quantity of which is equal to N. The alternating-current power source applies an alternating voltage commonly to the electrodes. One end of each of the capacitors is connected to a corresponding one of the electrodes, whereas the other ends of the capacitors are commonly connected to the alternating-current power source.

Abstract: A power converting apparatus includes a first inverter circuit including a high-voltage first DC voltage source and operated at a low frequency using Si IGBTs having a high withstand voltage exceeding 1000 V and a second inverter circuit including a low-voltage capacitor operated by high-frequency PWM using SiC MOSFETs having a low withstand voltage, wherein an AC side of the first inverter circuit is connected in series to an AC side of the second inverter circuit. The power converting apparatus outputs AC power having a prescribed voltage waveform obtained from the sum of voltages generated by the first and second inverter circuits.

Abstract: In a power conversion apparatus that boosts a solar light voltage, converts it to AC and supplies AC power to a load or system, power loss is reduced and efficiency is improved. An inverter unit, in which AC sides of three single-phase inverters receive DC power from respective sources with a voltage ratio of 1:3:9 as respective inputs are connected in series. Gradational output voltage control of an output voltage is carried out using the sum of the respective generated AC voltages. Also, a solar light voltage is boosted by a chopper circuit to generate the highest voltage DC power source. When the solar light voltage exceeds a predetermined voltage, the boosting of the chopper circuit is stopped, thereby reducing power loss due to the boosting.

Abstract: In a power conversion apparatus that boosts a solar light voltage, converts it to AC and supplies AC power to a load or system, power loss is reduced and efficiency is improved. An inverter unit, in which AC sides of three single-phase inverters receive DC power from respective sources with a voltage ratio of 1:3:9 as respective inputs are connected in series. Gradational output voltage control of an output voltage is carried out using the sum of the respective generated AC voltages. Also, a solar light voltage is boosted by a chopper circuit to generate the highest voltage DC power source. When the solar light voltage exceeds a predetermined voltage, the boosting of the chopper circuit is stopped, thereby reducing power loss due to the boosting.

Abstract: Provided is a highly efficient rectifier which can readily replace a two-terminal diode and whose conduction loss is reduced from that of the two-terminal diode. Connected between the source and drain of a MOSFET (2) including a parasitic diode (2a) are: a micro-power converter section (3) for boosting a conduction voltage Vds between the source and drain to a predetermined voltage; and a self-drive control section (4) that operates based on a voltage outputted from the micro-power converter section (3). When the source and drain are conductive with each other, the micro-power converter section (3) generates, from the conduction voltage Vds, a power source voltage for the self-drive control section (4), and the self-drive control section (4) continues drive control of the MOSFET (2).

Abstract: There are provided a smoothing capacitor (71) for storing an induced electromotive force generated by a three-phase induction motor (5), a regenerative transistor (81 to 86) for switching a terminal voltage of the smoothing capacitor to carry out a power regenerating operation over a three-phase AC power supply (3), a line voltage detecting portion (6) for detecting a line voltage of the three-phase AC power supply, a fundamental waveform generating portion (10) for generating, from a signal output from the line voltage detecting portion, a fundamental waveform defined to be a line voltage waveform of the three-phase AC power supply in which a source voltage distortion component is not mixed, a base driving signal creating portion (7) for creating a base driving signal to be used for an ON/OFF control of the regenerative transistor based on a signal output from the fundamental waveform generating portion, and a base driving signal output portion (9) for outputting the base driving signal.

Abstract: Three or more circuits including a driving inverter circuit and rectifier circuits are connected in series, each of the circuits including a high-voltage side MOSFET and a low-voltage side MOSFET connected in series as well as a smoothing capacitor having positive and negative terminals between which the MOSFETs are connected. LC series circuits, each including a capacitor and an inductor, are disposed individually between one specific circuit and the other circuits with periods of resonance of the LC series circuits made equal to one another. In performing DC/DC power conversion through charging and discharging operation of the capacitors, a resonance phenomenon of the LC series circuits is used to improve conversion efficiency and achieve a reduction in size of the apparatus structure.

Abstract: A three-phase inverter circuit (4) of which DC portion is smoothing capacitors (3) connected between output terminals of a solar battery (1) and single-phase inverters (5a-5c) connected in series with AC output lines of the three-phase inverter circuit (4) together constitute an inverter section, and this inverter section is connected to a three-phase power system (2). The three-phase inverter circuit (4) outputs a reverse-polarity voltage pulse (10ua) during a period within each of basic voltage pulses of which pulsewidth corresponds to a half cycle every half cycle of a system voltage. A power burden born by the individual single-phase inverters (5a-5c) in each half cycle is made approximately zero and the individual single-phase inverters (5a-5c) make a correction for subtracting a common voltage (Vo) from target output voltages of individual phases during the period when the reverse-polarity voltage pulse (10ua) is generated.

Abstract: A discharge-generation control unit applies at least a preliminary-discharge voltage pulse and a main-discharge voltage pulse between a wire electrode and a work. A discharge-position determining unit determines a discharge position from results of measurement by a plurality of current measuring units. A machining-energy adjusting unit adjusts machining energy generated by the main-discharge voltage pulse based on a discharge position determined before applying the main-discharge voltage pulse, and reflects a result of the adjustment on the generation of an electric discharge by feeding the result to the discharge-generation control unit.

Abstract: A DC/DC power conversion device includes n-stage circuits comprised of an inverter circuit for driving which is connected between positive terminals and negative terminals of smoothing capacitors, and a rectifier circuit which is connected between positive terminals and negative terminals of smoothing capacitors; a first circuit corresponding to at least one among the n-stage circuits and configured by connecting in parallel cell circuits of m, second circuits corresponding to a plurality of remaining circuits of (n?1) among the n-stage circuits; capacitors for energy transfer connected between middle points of the cell circuits and middle points of the second circuits; and column circuits of m comprised of the cell circuits, the second circuits and the capacitors for energy transfer, wherein the middle points are contact points of high voltage sided elements and low voltage sided elements of the cell circuits and the second circuits; and driving signals for driving the respective column circuits have the sam