Investigation of performance degradation of vector controlled single-phase induction motor drive under rotor time-constant variations

Flux vector control of single-phase induction motors allows fast torque response of the drive in response to load changes. Due to the decoupled components of the stator current, the rotor flux can be maintained constant while the electromagnetic torque is controlled independently. For achieving the correct field orientation, the angular position of the rotor flux with respect to the stationary reference frame needs to be determined accurately, using the slip frequency command and the rotor speed. However this computation relies on the rotor electrical time constant, which may change with operating conditions. This paper examines the effect of rotor time constant detuning on the performance of the drive. Results for dynamic and steady-state responses of the machine torque and flux are shown for a typical flux vector-controlled single-phase induction motor drive in both properly tuned and detuned cases.