Power converter and a three-phase AC power supply

A direct current unit (2,2,2) and three-phase AC (3) power converter for power conversion between the (100), the first phase converter, the second phase converter and the three-phase each converter (1,1,1) comprises a DC / DC converter circuit (10) and the single-phase power conversion circuit (11), the control unit (12), the first phase converter, the second phase transformation for each of the device and the three-phase converter (1,1,1), the absolute value of the voltage target value of alternating current, operates the DC / DC converter circuit (10) when above the DC voltage of the DC unit causes hold the absolute value of the voltage target value single-phase power conversion circuit (11) is a state of performing only the necessary polarity inversion, addition, absolute value, DC / DC converter circuit when below the DC voltage of the voltage target value (10) operates is operated to stop the single-phase power conversion circuit (11) of To hold the voltage target value each.