The non-complementary control strategy of Zeta mode three-level AC/AC converter

Abstract

Zeta mode three-level AC/AC converter can realize three-level voltage before output filter, which can get a better spectrum and reduce bulk of the filter. Compared with non-isolation and low or middle frequency isolation AC/DC/AC converters, it is single stage. And compared with Buck non-isolation AC/AC converter which can only realize buck output voltage, it can realize buck and boost output voltage. Zeta mode three-level AC/AC converter has four operation states in one period of input voltage and three different operation modes in one switching period. The non-complementary control strategy proposed makes the converter switch smoothly between different operation modes without any voltage spike. It also realizes non-complementary control in bidirectional power flow. As a result, the converter is suitable to different kinds of loads. It doesn't need to think over dead-time and its bad effects.