A Novel Modulation for Soft-Switching Three-Phase Quasi-Z-Source Rectifier Without Auxiliary Circuit

A new space vector modulation, i.e., ZSVM3, for three-phase quasi-Z-source rectifier (qZSR) is proposed. All switches in the three-phase bridge can be turned on and turned off with zero current or zero voltage using the proposed ZSVM3 with no auxiliary circuit. The current through the inductors of the quasi-Z-source network operates in a boundary conduction mode or discontinuous conduction mode to achieve all freewheeling diodes turned off with zero-current switching (ZCS). At the same time, the switch in the quasi-Z-source network can be turned on with ZCS. Besides, the voltage stress of all switches is equal to dc-link voltage. The operation principle of the qZSR is analyzed in detail, and the calculated value of the quasi-Z-source inductor is given. The proposed theory in this paper is verified by a 2-kW prototype.