A control unit of an electric power converter, which is used in a three-phase motor having two winding wire systems, performs for a first duty instruction signal regarding a voltage applied to a first winding wire group a flatbed two-phase modulation process, and performs for a second duty instruction signal regarding a voltage applied to a second winding wire group a flattop two-phase modulation process. By phase-shifting the second duty instruction signal by 30° from the first duty instruction signal, a timing of maximum value of the first duty instruction signal is shifted from a timing of minimum value of the second duty instruction signal. Even when the maximum value is greater than a center output value and the minimum value is smaller than the center output value, overlapping of capacitor discharge is avoided, thereby reducing a ripple electric current.