PhD Thesis - Cranfield University

Chapter 4
CHAPTER 4
ELECTRIC VEHICLE POWER AND ENERGY
REQUIREMENTS
“ Truth is ever to be found in the simplicity, and not in the multiplicity and confusion of things”
Isaac Newton, 1642-1727
This chapter describes the power and energy requirements of land based electric vehicles.
The various operating modes that the vehicle is subjected to throughout a mission profile are
presented in order to analyse the instantaneous tractive power requirements and net energy
expenditure. To approximate the power and energy requirement parameters, the longitudinal
dynamics of the vehicle is examined. The derivations of parameters that influence the vehicle
tractive efforts are based on Newton’s second law of motion. After describing the vehicle
kinetics, an empirically validated vehicle model developed using SIMPLORER® is
presented. Using this vehicle model, two industry standard drive profiles followed by a
modified drive profile are examined to illustrate the effect of arbitrating power flow for a
battery and ultracapacitor energy storage system. Using a VHDL-AMS model for the battery
system and a simplified first order model for the ultracapacitor system, simulations are
presented to show the segmentation of a vehicle power demand spectrum.
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