PhD Thesis - Cranfield University

Chapter 1
In the past, many research works were targeted at overly ideal systems to theoretically
demonstrate the general concept of power and energy management. Although detailed
models have also been considered, the majority of previous work in this area involves non-
causal approaches to achieve some closed-form analytical solution. Complete
implementation and systematic procedures are rarely considered. The identification of this
limitation in present literature leads to the investigation of more practical design methods.
To form a structured systems level method that is able to encompass the complete
implementation of a power and energy management system, general concepts and theory
derived from traditional hierarchical management methodology are utilised. In addition,
frameworks established from stochastic decision theory as well as intuitive reasoning of the
general problem help create a structured modular process that presents a more systematic
design methodology.
In this work, an attempt is made to include all relevant practical components and subsystems
in order to produce results that are directly relevant to practical designs. It is expected that
significant findings that are unattainable with purely theoretical approaches can be
uncovered when practical systems are considered. To achieve this, a pure electric vehicle
consisting of batteries as the main energy source and ultracapacitors as the peak power
source is designed and constructed. The vehicle serves as a platform and experimental
facility to demonstrate or even disprove the effectiveness of the hypothesized power and
energy management implementation methodology. The hardware is developed based on the
application requirements and constraints of the test vehicle and energy storage units.
The design process begins by identifying the physical and operating constraints of both
battery and ultracapacitor technology. Subsequently, subsystem models and baseline design
parameters are obtained through iterative simulations, experimental verifications and
reference to literature. As the modelling platform, the Advanced Vehicle Simulator
(ADVISOR) systems level simulation tool and the SIMPLORER simulation package are
used extensively. Fuzzy logic theory is employed to implement the heuristic reasoning of
energy management.
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