Bidirectional multilevel converter for electric vehicles

Abstract

In this paper is presented an H-Bridge Multilevel Converter topology for Electric Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs). The topology of the presented multilevel converter allows the interface between the batteries, the electric motor of the vehicle, and the electrical power grid. Thereby, taking into account that the proposed multilevel converter requires the use of isolated voltage sources, the interface between the batteries and the multilevel converter is evaluated regarding the converter operation as a Battery Management System (BMS), controlling the charging and discharging processes. The interface between the multilevel converter and the electrical power grid is described considering a bidirectional operation. These modes of operation occur during the batteries charging process, denominated as Grid-to-Vehicle (G2V), and during the operation as Vehicle-to-Grid (V2G), that consists in delivering back to the electrical power grid a small amount of the energy stored in the batteries, in accordance with the electrical grid requirements and with the vehicle driver accordance. In both modes of operation, the waveform of the AC current of the electrical power grid is kept sinusoidal with unitary power factor, contributing to maintain a good level of power quality.