Power conversion apparatus

A power conversion apparatus comprising:

• two power conversion circuits including a first power conversion circuit and a second power conversion circuit, the first power conversion circuit being connected in parallel to a direct-current load or a single-phase alternating-current load, the second power conversion circuit being connected in parallel to a three-phase alternating-current load;
• two direct-current inductors including a first direct-current inductor and a second direct-current inductor;
• and
• a pulse-width-modulation control circuit configured to pulse-width-modulate the two power conversion circuits,
• wherein the two power conversion circuits are current-type inverters, and are connected in reverse polarity to each other via the two direct-current inductors;
• and
• the pulse-width-modulation control circuit allows switching between the two power conversion circuits and realizes a bidirectional step-up/down operation between the direct-current load or single-phase alternating-current load and the three-phase alternating-current load,
• wherein the pulse-width-modulation control circuit includes
• a control calculator configured to output an acceleration/regeneration signal indicating a direction of power conversion, a converter duty factor λc, an inverter duty factor λi, and a current phase command θi* by using inter-phase voltages of the three-phase alternating-current load, a current Idc flowing in the two direct-current inductors, and an inter-terminal voltage VRS of the direct-current load or single-phase alternating-current load;
• a carrier generator configured to output an uneven carrier waveform for varying a time ratio in accordance with the converter duty factor λc, and output a carrier-period determination signal;
• a current-type pulse-width-modulation calculator configured to generate drive signals S1* to S6* on the basis of the uneven carrier waveform, the inverter duty factor λi, and the current phase command θi*;
• and
• a pulse distributor configured to distribute the drive signals S1* to S6* to the two power conversion circuits on the basis of the acceleration/regeneration signal and the carrier-period determination signal.