an investigation of dual stator winding induction machines

The system in which a PWM converter is shunt connected with capacitors and loads
is called PWM converter assisted induction generators as shown in Figure 1.4(a). The
PWM converter with dc capacitor in this topology functions as a variable and
controllable three-phase capacitor. The advantage of this topology is that with the
reduced power rating of the PWM converter the system cost can be reduced. However,
the complexity of the system is increased. The other one with absence of a three-phase
excitation capacitor is called PWM converter driven induction generator, in which the
three terminals of induction generator are connected to PWM converter only as shown in
Figure 1.4(b).
The PWM converter assisted induction generator system was proposed in [8.18],
where an indirect stator flux control strategy is adopted and the system steady state and
dynamic operation is studied. Similar system topology is found in [8.19], where the
analysis, design and selection of PWM converter components were presented for five
different power rating machines with varying power factor loads. However, the PWM
converter in [8.18] and [8.19] can only absorb or inject reactive power into the system
because of the absence of dc sources. In [8.20], a battery bank is paralleled with dc
capacitor such that it can absorb and inject both active power and reactive power thus
increasing the efficiency and availability of the system.
In [8.21], an inverter driven induction generator has been proposed and a theoretical
treatment based on a first harmonic approximation of inverter performance was
presented. It has been concluded that the inverter makes the development of efficient
induction generators capable of operating over wide speed ranges [8.21]. A strategy to
control an induction generator working with variable speed and load was presented in
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