Complete Equivalent Circuit
The rotating air gap flux generates back e.m.f. (E1) in all the three phases of the stator. The stator applied terminal voltage V1 has to overcome back e.m.f. E1 and the stator leakage impedance drop:
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(14) |
The stator current I1 consists of following two components, I1' and Im. The component I1' is the load component and counteracts the rotor m.m.f. The other component Im creates the resultant air gap flux Φm and provides the core loss. This current can be resolved into two components: Ic in phase with E1 and IΦ lagging E1 by 90°. In the equivalent circuit of the stator shown in Figure 6 , Ic and IΦ are taken into account by a parallel branch, consisting of core-loss resistance Rc in parallel to magnetizing reactance XΦ.
The rotor e.m.f. E2 when referred to stator become
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(15) |
The rotor leakage impedance when referred to the stator is
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(16) |