Modeling energy and power requirements of electric vehicles

Abstract

In this paper we present a model of electric vehicle performance that can be used to estimate energy and power requirements of vehicles in various driving environments. The model is developed from basic vehicle parameters and, when coupled with a simple model of battery performance, is used to examine effective ranges and per-mile traveled energy requirements of electric vehicles as compared with internal combustion powered vehicles under similar driving conditions.

A number of classes of vehicles are discussed, each of which is identified by characteristic values of the model's vehicle and driving pattern parameters. A simplified driving cycle is adopted and range calculations are made on each of the vehicle classes using a simple model of battery performance for a typical lead-acid battery and for a theoretical high-performance battery.

The relationships developed here not only provide a simple estimating model of vehicle performance, but also lay the groundwork for a more comprehensive simulation model, the development of which is currently in progress. The simplified model has a number of restrictions on modeling alternative driving patterns. These restrictions are discussed along with logical extensions to the model that address the restrictions.

The preliminary results of the model indicate that electric vehicles, employing either current technology or high-performance batteries, may be energy efficient in urban environments. However, in inter-city applications, where internal combustion engines are most efficient, the comparative energy efficiency of electrics is minimal.