SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

Organization
This report is organized into the following chapters and appendices.
Chapter 2 – “Fundamentals of Electric Motors” – presents some fundamentals of electric motors
and their models, eventually narrowing the focus to the brushless permanent magnet
(BPMS) motor that is the subject of this report. The basics of motor structure and
terminology are discussed, followed by a fundamental examination of the physical laws
that govern motor operation; this leads to the general per-phase electrical model for a
winding that will be used throughout the report. In addition, the derivation provides a
foundation for understanding inductance in a motor winding and demonstrates the
significance of the magnet’s leakage permeance on the magnetic circuit. Then torque
production and back-EMF generation are investigated on a per-phase basis. This forms a
basis for understanding polyphase motor operation and enables the full phase-variable
electromechanical model of the polyphase motor to be developed. In the last section, the
two theoretical types of BPMS motors are discussed and torque and back-EMF are then
investigated for these two motors. This examination of torque production forms a natural
introduction to current commutation.
Chapter 3 – “Sinusoidal BPMS Motors” – is the most important chapter and comprises the bulk
of the report. Its ultimate purpose is to develop a space vector model for the sinusoidal
BPMS motor because that model and its understanding (reference frame theory) are the
basis for all modern motor modeling and control schemes. In order to achieve this goal
the chapter is split into three parts. In Part I the standard analysis of sinusoidal
synchronous machines is presented in the time and phasor domains. Part II introduces and
discusses the space vector definition, notation, and interpretation by building on the
understanding of the synchronous machine presented in Part I. Finally, Part III applies the
space vector concepts from Part II to the modeling material from Part I to yield the space
vector model of a BPMS motor.
Chapter 4 – “Inverters and Space Vector Modulation” –reviews inverter topologies and basic
principles, concentrating on the voltage-source inverter (VSI). Space vector modulation
(SVM) is introduced by building on the six-step 180° squarewave inverter. The
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