An electric power conversion apparatus includes a power converter connected to at least a first DC voltage source, a second DC voltage source and an AC electric motor. A control unit controls the power converter to generate a first PWM pulse train for supplying a first output voltage pulse train from the first DC voltage source to the AC electric motor and a second PWM pulse train for supplying a second output voltage pulse train from the second DC voltage source to the load in such a manner to form a pulse continuous in time in a final output voltage at least from each pulse of the first output voltage pulse train and a subsequent pulse of the second output voltage pulse train. A current path is provided constantly from the AC electric motor to at least one of the DC voltage sources.