# What's the point of vector control for ac machines?

for what I understood vector control controls the rotor's flux and the torque (both in magnitude) by changing the stator currents in the qd0 reference frame.

let's say we are dealing with direct vector control for simplicity:

in DC machines the rotor magnetic field is always orthogonal to the stator, and this is the goal in PM machines control too (to maximise the torque with using the minimum current, basically the Max torque per Amp problem).

Is this the goal here too? One thing I don't really get is how the flux has a phase if it's a scalar (and this phase seems to be on the D axis, so the same as the rotor's magnetic field), but maybe is an abuse of notation?

I believe my question could be translated in: given a desired torque and speed, will the control drive the rotor flux to be orthogonal (if it even makes sense for fluxes) to the stator's, or this may not be the case since the goal of this type of control is another?