Stator and rotor representation by equivalent dq winding currents.
The dq winding voltages are defined as positive at the dotted terminals. Note
that the relative positions of the stator and the rotor current space vectors are
not actual, rather only for definition purposes.
windings equals Lm. Out of four dq windings, the mutual inductance
between any d-axis winding with any q-axis winding is zero because of
their orthogonal orientation, which results in zero mutual magnetic
coupling of flux.