EV battery charger that uses Z-source AC/AC converter

In this paper, a simple and low cost AC/AC/DC converter is proposed to charge EV( Electric Vehicle) batteries. An exclusive Z-Source (LC) network, which acts as a static transformer, is connected in front of the PI filter and uncontrolled full-bridge rectifier. By controlling the shoot-through duty ratio, the output voltage of the converter can be regulated in a large range rapidly, which can meet the charging demands of EV battery series in different scales. Compared to the conventional charger, the bulk is small. In this topology, fewer switches are needed. It´s safer, doesn´t need to take account of the dead zone and the control strategy is simpler. More over, inheriting the advantages of Z-source, the novel charger reduces in-rush and harmonic current, which makes it more flexible to the grid. The qualitative and quantitative analysis of the proposed topology and the control method are presented. Simulations of charging polymer Li-ion battery series are given, and the results prove the validity of the analysis, and verify the good application of the novel EV battery charger.