In power conversion according to the three-phase converter, symmetrical component voltage values of a balanced system are calculated from wye-phase voltages on the three-phase AC input side of the three-phase converter. On the DC output side thereof, the power factor is set, an average active power value is calculated from an output voltage value and an output current value, and an average reactive power is calculated from the set power factor. On the basis of the symmetrical component voltage values, the average active power, and the active reactive power, a compensation signal for compensating for unbalanced voltages of the three-phase AC voltages and a control signal for controlling the power factor are generated, and according to the compensation signal and the control signal, a control signal for outputting DC is generated.