The method comprising by the controller using the required torque and the rotational speed of the first motor and the second motor deriving the first motor and the required maximum voltage and the minimum required voltage of the second motor; Deriving the first motor and the voltage command of the second motor with the speed of rotation and the magnetic flux of the first motor and the second motor in the control unit; Deriving a correction voltage control using the voltage command of the first motor and the second motor in the control unit; In the control unit deriving the first motor and the required maximum voltage, minimum required voltage, the correction voltage command and the converter output voltage command by using the battery voltage of the second motor; And the step of controlling the output voltage of the converter using the output voltage command from the control unit; the converter control method of a vehicle including a is introduced.