Difference between machine types is merely a matter of flux generation: $\vec{\psi}_s = L_s \vec{i}_s$ (IM), $\vec{\psi}_s = L_s \vec{i} s + \vec{\psi} {PM}$ (PMSM), or $\vec{\psi}_s = L_s \vec{i}_s + L_m \vec{i}_r'$ (DFIM). The drive —the control algorithm—does not need to know the difference beyond the flux linkage map.
This monograph does not seek to replace the classic texts of Fitzgerald, Leonhard, or Novotny & Lipo. Rather, it aims to re-center the student and practitioner onto the structural invariant : the rotating space vector is the real physical quantity; the three phase windings are merely its projection sensors. From this vantage point, electrical drives become a branch of applied vector calculus, not a catalog of special cases. Difference between machine types is merely a matter
where $\omega_k$ is the speed of the chosen reference frame (stationary, rotor, synchronous). The torque expression unifies as: Rather, it aims to re-center the student and