Synchronous modulation method for three-level converter under even-number-multiple carrier ratio of 3

The invention discloses a synchronous modulation method for a three-level converter under an even-number-multiple carrier ratio of 3. The method comprises the following steps: defining a zero-sequencecomponent U0 = (1-(Umin + Umax))/2, and performing the superposing of the zero-sequence component U0 through a three-phase sine wave to obtain a three-phase modulated wave; simultaneously generatingtwo groups of in-phase stacked triangular carriers with a phase difference of 180 degrees, and selecting one group, which cannot cause phase voltage two-level jump, in the two groups of triangular carriers as an actual comparison triangular carrier at a first sampling point after modulating wave phase angles of 0 degree, 60 degrees, 120 degrees, 180 degrees, 240 degrees and 300 degrees; defining Cas a carrier ratio, and achieving the synchronous modulation of the three-level converter for C/2 + 1 times based on comparison of an actual comparison triangular carrier and a three-phase modulationwave on the premise of ensu