Improvement of Multilevel DC/DC Converter for E-Mobility Charging Station

Considerable efforts are being made to reduce CO2 emissions and thereby solve the problems of environmental pollution and global warming. Technologies for environmentally friendly transportation are being developed using batteries. In particular, with the increase in urbanization and one-person households, e-mobility products are drawing increasing attention as short-distance transportation devices. Among these vehicles, personal mobility devices (PMDs) are receiving attention as new transportation devices that are simple to operate. This paper proposes a new multilevel charging system that is advantageous in responding to the charging voltage specifications of various mobile devices with a single charging system while ensuring a low charging current ripple. The proposed diode-parallel multilevel converter consists of an independent Buck converter in series. The switch of the buck converter is configured at the negative terminal of the input power source so that the gate amplifier voltage is used as the power supply voltage; it can therefore be simply configured without a separate gate amplifier power supply. In addition, it is improved so as to have a wider charging voltage range in a low output voltage region and a better efficiency than the existing diode series multilevel converter. To verify the feasibility of the proposed system, simulations were performed using the software PowerSIM(PSIM), and, in order to verify the validity, a prototype charging system was fabricated to compare and analyze losses according to operating conditions.