Novel Three-Phase Current-Fed Z-Source AC-AC Converter

The paper proposes novel topologies of PWM ac-ac converter with minimal number of switches: three-phase current-fed Z-source converter. By PWM duty ratio control, they become "solid-state transformers" with a continuously variable turns ratio. They employ only two switches. Compared to the existing PWM ac-ac converter circuits, they have unique features: reducing in-rush and harmonic current, and improving reliability. The operating principle and control method of the proposed topology are presented. Analysis and simulation and experimental results are given, and the simulation and experimental results verify the rationality of the proposed ac-ac converter topologies.