ABSTRACT
The previous chapter dealt with the principles of synchronous generators (SGs) and steady state based on the two-reaction theory. In essence, the concept of traveling field (rotor) and stator magnetomotive forces (mmfs)
and airgap fields at standstill with each other has been used. By decomposing each stator phase current under steady state into two components, one in phase with
the electromagnetic field (emf) and the other phase shifted by 90
°
, two stator mmfs, both traveling at rotor speed, were identified. One produces an airgap field with its maximum aligned to the rotor poles (
d
axis), while the other is aligned to the
q
axis (between poles). The
d
and
q
axes magnetization inductances
X
and
X
are thus defined. The voltage equations with balanced three-phase stator currents under steady state are then obtained.
