Fuzzy Adaptive Controller for a DFI-Motor - Complex System Modelling and Control Through Intelligent Soft Computations - page 91

at frequency proportional to the stator supply frequency. For all speed ranges the
stator and the rotor angular frequencies are related to the shaft mechanical speed by
x s ¼ x r þ x

.
Expressions of stator and rotor active and reactive powers are respectively given by

P s ¼ u sd i sd þ u sq i sq

u sq i sd þ Q s ¼ u sd i sq

ð 5 Þ

P r ¼ u rd i rd þ u rq i rq

Q r ¼ u rq i rd þ u rd i rq

In the following section, the control objective of the DFI-Motor will be discussed.

3 DFI-Motor Control Objective

First, we suppose that the stator flux vector is aligned with d-axis as shown in

Fig. 1 . In the stationary frame abc, the component n of the stator voltage equation is
given by

fl

d u sn

dt

u sn ¼ R s i sn þ ð 6 Þ

By neglecting the stator resistance (Hopfensperger et al. 2000 ), ( 6 ) can be
written as

d u sn

dt

u sn ð 7 Þ

This equation demonstrates that the stator voltage vector is 2

in advance of the

stator fl flux. Then, in the chosen reference frame, we can write

u sd ¼ 0

ð 8 Þ

u sq ¼ u s

Fig. 1 Reference frames and
angles for DFI-Motor

ʲ − Rotor ʲ − Stator

ˉ

q

s

˕

d

s

ˉ

u

s

ʸ ʱ − Rotor

ʸ r

1

ʸ

s

ʸ

ʱ − Stator