A multiplexed inverter topology cascaded by line voltage is proposed, which composes three modules: PV panel, quasi-z source network and three-phase inverter. Through an analysis of the function feature of established mathematical model, an improved dual-loop control system is proposed. Voltage boost is added in the improved dc side, where 180V PV input voltage of each module can realize 380V direct grid-connection without transformer. Costs and switch frequency are decreased. The proposed control methodology is fit in three-phase grid-connection generation system with new energy.