I am stuck on the concept of individually controlling the orthogonal components of the stator current vector in an AC induction motor.
Physically, I just don't see it.
In principle, you can apply any desired voltage waveform to the stator winding, with the desired Fourier (one or two r's?, it's been a long time)components.
Granted you are controlling the inductive impedances this way.
My brain melts after that.

 

> I am stuck on the concept of individually controlling the orthogonal components of the stator current vector in an AC induction motor.<

It is not possible to control the two currents individually because of a simple reason: You have only *one* controllable output (voltage waveform), however *two* almost independent process variables (magnetization and torque currents).

In fact, practically you do not need to control the magnetization current, but you have to measure (or estimate) it. As you calculate the magnetization current, you can control the torque producing current. This is what vector controlled drives do.

In a DC motor, the two currents can be controlled independently, because there are two outputs and two process variables (armature and field voltages/currents).