Power conversion device and three-phase AC power supply device

摘要

A power conversion device comprises: a conversion device (100) for each phase, said conversion device converting a DC voltage input from a DC power supply (5) to an AC waveform voltage to be output to each phase with respect to the neutral point of three-phase alternating currents; and a control unit (3) for controlling each conversion device (100). Each conversion device (100) has a DC/DC converter (10) including an insulating transformer (12) and a capacitor (14) and comprises: a first conversion unit (1) and a second conversion unit (2). The first conversion unit (1) converts an input DC voltage to a voltage including a pulsating waveform by controlling the DC/DC converter (10) by the control unit (3), said pulsating waveform corresponding to the absolute value of the voltage obtained by superimposing a third-harmonic wave onto a fundamental wave as an AC waveform to be output. The second conversion unit (2) is provided at the stage next to the first conversion unit (1), has a full-bridge inverter (21), and converts the voltage including the pulsating waveform to an AC waveform voltage by inverting the polarity thereof on a per cycle basis by controlling the full-bridge inverter (21) by the control unit (3).