Grid connected quasi-Z-Source direct matrix converter

This paper proposes a new three-phase ac-ac converter topology based on the Z-source concept and the conventional direct matrix converter (DMC), it is called quasi-Z-Source direct matrix converter (QZSDMC). It could provide buck-boost function and make the role of frequency changer. Compared with the traditional ac-dc-ac converter, it uses fewer devices and realizes direct ac-ac power conversion, so as to have higher efficiency and better circuit characteristics. Compared with the traditional direct matrix converter, it provides wider voltage regulation range and improves input-output voltage transformation ratio. The proposed converter is tested as a grid connected converter for interfacing renewable energy sources. The circuit topology, operating principle, control method and simulation results are given to verify the feasibility of the proposed converter.