An electric power converter, electric power conversion system and method that, without using a DC-DC converter, uses and allots the electric power of plural power sources while reducing the volume and losses. At least one phase of the motor is connected to plural power sources and generates and synthesizes pulses from output voltages of plural power sources so as to drive the multi-phase AC motor. A different phase of the motor is connected to one DC power source and generates pulses from the output voltage of the power source so as to generate a driving voltage for the multi-phase AC motor. This arrangement allows use/allotment of the power of plural power sources with a reduced number of semiconductor components.