Fuzzy logic based speed control and slip compensation for rotor time constant variations in a field-oriented induction motor drive

Indirect field oriented (IFO) induction motor drives can provide fast dynamic torque response and track rapid changes in reference speed and load torques. However the decoupled control of torque and flux is affected due to variations in the rotor electrical time constant. As a result, the drive performance is seriously degraded, unless some form of adaptation is employed. This paper presents an IFO drive consisting of two fuzzy controllers, which respectively regulate the rotor speed and adjust the applied slip frequency as a result of detuning. The proposed drive is shown to regulate the rotor flux and maintain field orientation under a wide range of rotor time constant variations.