Electric vehicle fast charger high voltage input multiport converter topology analysis

Abstract

This paper describes a novel topology for a multiport electric vehicle battery charging converter. Due to high energy demand and high input currents, a fast-charging station is placed close to the substation that contains a low frequency transformer. Inside the fast-charging station, an intermediate DC-bus connects energy storages, a supply grid rectifier and charging converters. Low voltage (570 V) causes high currents and results in high losses at busbars, magnetic components and semiconductor devices. We propose a high voltage input multiport converter topology with a high frequency isolation transformer for a fast charger of an electric vehicle. High input voltage enables currents and conduction losses to be kept low in the charging converter until the very last conversion stage that is connected to the electric vehicle battery. Also, the dimensions of magnetic components are reduced due to high frequency. Grid-side converter is realized using the back to back cascaded converter topology. Charging converters can be realized with the current doubler rectifier topology and bidirectional with a controllable full bridge rectifier/inverter as in this operational mode it has an advantage over a current doubler. The quasi Z source could be used as a filter/boost circuit. The proposed charging station topology was verified by computer simulations.