Abstract:
Use of conventional induction machines (IM) in adjustable
speed drives (ASD) has increased in recent years. Electronic
power processing has facilitated this increased use. The IM
is an inexpensive and robust machine, but when used as part of
an ASD, the cost of the system increases due to the inclusion
of the power electronic converter. By using a single frame
cascade induction machine (also referred to as a Brushless
Doubly-Fed Machine or BDFM), which was first introduced in
1907 by Hunt [1], in conjunction with a power electronic
converter, an alternative ASD system can be developed. The
BDFM allows lower overall system cost since the power
electronic converter is only required to process a fraction of
the total power. The bulk of the power is fed directly from
the 60 Hertz utility supply to the terminals of the machine.
Redacted for Privacy
This thesis details the analysis of the EDFM by use of
computer simulation; the simulation is an updated detailed
model first described by Wallace et al. [8-9]. The program
gives time domain information on stator and rotor component
currents as well as mechanical shaft speed. Development of a
brushless castable rotor is presented. Design improvements to
the basic rotor are discussed by changing rotor loop spacing
and removal of rotor bars. Stator design is explored by
varying the span and distribution of a double layer winding
which allows two fields of different pole number to be
produced by one stator. Further, employment of two isolated
stator windings is discussed. Finally, predicted performance
of the machine by simulation is compared qualitatively with
actual machine measurements from a physical prototype to
highlight the use of the simulation as a design tool.
