Comparison of Direct and Indirect Vector Control of Induction Motor

Vector control is becoming the industrial standard for induction motor control. The vector control technique decouples the two components of stator current space vector: one providing the control of flux and the other providing the control of torque. The two components are defined in the synchronously rotating reference frame. With the help of this control technique the induction motor can replace a separately excited dc motor. The DC motor needs time to time maintenance of commutator, brushes and brush holders. The main effort is to replace DC motor by an induction motor and merge the advantages of both the motors together into variable speed brushless motor drive and eliminate the associated problems. The squirrel cage induction motor being simple, rugged, and cheap and requiring less maintenance, has been widely used motor for fixed speed application. So with the implementation of vector control, induction motor replaces the separately excited dc motor. The vector control technique is therefore a better solution so that the control on flux and torque become independent from each other and the induction motor is transformed from a non-linear to linear control plant. With the advent of field oriented control; the induction motor has become an attractive option. In this report we will come to know the concept of vector control and different types of vector control techniques available. And finally we will be able to compare them.