The Influence of Odevity of Carrier Ratio on Three-level Rectifier

Neutral point voltage balancing is an inherent problem of three-level rectifier. This paper first analyzed the cause to the neutral point voltage deviation of the DC-side three-level rectifier, and studied the charge and discharge transient processes of the two DC-side capacitors and the harmonic characteristics of the current of the AC-side rectifier respectively when the carrier ratio is an odd number or even number. It also verified its studies through simulation. The results showed that, when the carrier ratio is an even number, the neutral point voltage of the three-level rectifier is more easily to be balanced and will not cause bad influence on the harmonic characteristics of the AC-side rectifier.