Techniques for estimating the residual range of an electric vehicle

This paper presents an algorithm that has been developed to estimate the residual range of an electric vehicle, i.e., the distance that can still be covered with the energy stored inside the battery. The algorithm takes into account the complexity of the behavior of electrochemical batteries, with special reference to lead-acid batteries, as well as the main issues related to different driving styles. This paper also discusses some of the experimental results obtained by the use of the algorithm in several urban test trips made using two different types of electric vehicles.

I. Introduction

It is acknowledged by all the technicians that work in the field of electric vehicles (EVs) that they constitute a real alternative to vehicles powered by internal combustion engines for urban traffic in a large number of cases. However, despite the continuous progress in storage battery technology, EVs are, and will remain for the foreseeable future, characterized by a much smaller range than that of conventional vehicles, because of the much lower energy that can be stored per unit of mass (or of volume) in electrochemical batteries with respect to fossil fuels. As a consequence of this reduced range, it is of the greatest importance to have precise and reliable estimates of the residual range, i.e., the distance that can still be covered with the energy stored inside the battery. This way, a very large part of the available range can be safely exploited by the user.