# Vector Control in Induction Motors

Can vector control in induction motors be considered as power factor correction ? From my researchs, it seemed to me angle between rotor and stator flux is 90 degree when load is purely resistive (power factor is unity).The goal of vector control is to make this angle 90 and get the maximum torque. Is that right ?

Only in a very nonstandard sense. Vector control of an induction motor pertains to the power (possibly the instantaneous power) going to the motor. Yes, it's may be good in some cases if this power is, for the most part, real.

However, to most engineers "power factor correction" will mean the ratio of real to reactive (or harmonic) power at the point of connection to the power grid -- and that's not where vector control happens.

• Thanks for your answer So we can say method in basic is similar but where we apply it and the way applying is different. Jun 16 '19 at 8:50

It's not about active/reactive power.

Vector control in a drive simply says your control loop is fed with the phase-corrected momentary I/U parameters instead of I/U averaged over several periods.

The goal of vector control is having a finer and faster response to torque changes from the load, as there is no low-pass and averaging over several periods.

• Thanks for your answer So we can say method in basic is similar but where we apply it and the way applying is different Jun 16 '19 at 9:04
• Again, vector control is not about holding the phase angle between U and I at 0°. That would mean power factor correction (of the fundamental wave). You cannot have an induction motor with zero reactive power either. Reactive power is needed for its function. At zero reactive power, there would be no slip between stator field and rotor and thus, no torque. Jun 16 '19 at 12:05

"Vector Control" is a terminology that only applies to the OUTPUT of a VFD in terms of performance response and accuracy. It has no relationship to what happens on the LINE SIDE input of ta VFD.

That said, a standard "6 pulse" VFD, by virtue of what it is doing, in effect will correct the displacement power factor of the power INTO the VFD rectifier to near unity, but then adds some distortion power factor in the form of harmonics. If your utility is not capable of measuring the higher frequency distortion power factor, you may appear to be at .95 displacement PF or better. But this has nothing whatsoever to do with the output being vector control or not.