Torque behavior of a RFO induction motor drive under voltage sag conditions

Industrial processes equipped with adjustable speed drives have shown to be very vulnerable towards voltage sags. In many applications, the control of torque and/or speed is the main interest in order to maintain proper operation. This paper investigates the behavior of a rotor flux oriented (RFO) induction motor drive under voltage sag conditions. The maximum torque as a function of the mechanical speed and disturbed DC-link voltage is determined. Finally, the results are used to set the undervoltage limit of the drive to an appropriate value.