Performance characteristics of speed-sensorless vector control of parallel connected induction motor drive

This paper presents the speed characteristics of a sensorless vector control of two induction motors of same rating connected in parallel and fed by a single inverter. Speed and rotor fluxes of both drives are estimated by natural observer. The speed difference between two induction motors is reduced under unbalanced load conditions by employing additional PI controllers in the speed control loop even though mean value of rotor fluxes and stator currents are considered. The mean value of rotor flux is maintained constant by rotor flux feedback control. Simulation results are presented under unbalanced load conditions to prove the effectiveness of the given method.