To reduce capacitance of a capacitor for smoothing by smoothing voltages of a plus and a minus DC voltage buses which are used in common by a plurality of inverters for driving a plurality of motors.
Phase difference of carriers in PWM control is set as 90 degrees when two motors are together in the driving state or in the damping state (S104), and phase difference of carriers in PWM control is set as 180 degrees when one is in the driving state and the other is in the damping state (S106). By setting the phase difference of the carriers as 90 degrees when both of the motors are in the driving state or in the damping state, pulses of an inverter flowing-out current which pulses correspond to the respective motors are made to appear alternately, and voltages of the plus and the minus DC voltage buses are smoothed. By setting the phase difference of the carriers as 180 degrees when one is in the driving state and the other is in the damping state, pulses of an inverter flowing-out current which pulses correspond to the respective motors are canceled, and voltages of the plus and the minus DC voltage buses are smoothed. As a result capacitance of the capacitor for smoothing can be reduced.
MORIYA KAZUNARI
SHIYAMOTO SUMIKAZU
OKI RYOJI
SASAKI SHOICHI
TOYOTA MOTOR CORP