Tema da Tese: ‘Sistema Integrado para Tração e Carregamento de Baterias de Veículos Elétricos com Interface Universal com a Rede Elétrica’

Autor: Tiago José da Cunha Sousa

Orientadores: João Luiz Afonso; Vítor Duarte Fernandes Monteiro

Data: 22/04/2022

Programa Doutoral: Engenharia Eletrónica e de Computadores

Abstract

The consumption of electrical energy has been increasing decade by decade since last century. This increase has been leading to a continuous energy resources shortage, as is the case of fossil fuels which, in an aggravating way, have the disadvantage of contributing to the greenhouse effect, causing damage to the planet. In an effort to alleviate fossil fuels dependency, electric vehicles (EVs) appear as one of the most promising agents towards a sustainable planet with lower levels of environmental pollution.

Besides the electric mobility paradigm, the EV plays a decisive role as a power grid support mechanism, since it is possible for battery charging systems to allow bidirectional operation. Hence, it is expected for the EV to be part of the solution instead of the problem for the power grid point of view, i.e., avoiding its congestion due to simultaneous battery charging of several EVs. It should be referred that electrical power quality must be also taken into consideration regarding EVs.

Regarding the power electronics converters that integrate an EV, conventionally based on a traction system to drive the electric machine and a battery charging system that is used for slow battery charging, an approach can be performed towards converter optimization, namely by unifying both systems. With such approach, it is possible to drive the EV electric machine and perform the interface with the power grid for battery charging operation using the same power converters, which not only reduces the weight and cost of the employed power electronics but also endows the EV with an on‑board fast battery charging system.

In this context, the present document has as main goal the proposal of an integrated system for traction and battery charging of EVs with the possibility of interfacing power grids of the alternating current (AC) type, namely single‑phase and three‑phase AC power grids, and with power grids of the direct current (DC) type, using the same equipment in all cases. Furthermore, all interface modes allow bidirectional operation, therefore not restraining the EV to the operation as a mere load to the power grid but also as a support mechanism, being able to behave as such in any of the aforementioned types of power grids. The system proposed in this dissertation is initially validated through computational simulations, being afterwards designed and assembled an experimental prototype which was then validated in a workbench.

Keywords: Battery Charging Systems, Electric Vehicles, Integrated Systems, Smart Grids, Traction Systems.