Modelling analysis and simulation of motor parameter variation in vector controlled electrical drives

The aim of this paper is to compare the influence of parameter uncertainties on the performance of two vector-oriented control schemes of an induction motor drive. In the first, the field-oriented control method is used to control the speed of the induction motor. In this system, the spatial vector of the stator current is transformed into a i/sub 1q/ component which creates the torque, and into a i/sub 1d/ component which creates the flux. If the d-axis component of the stator current is of a constant value, the motor drives with a constant flux and the torque can be altered rapidly by means of the q-axis component of the stator current i/sub 1q/. Two components U/sub 1d/,U/sub 1q/ of stator voltages in the d-q coordinate system, which must be applied to the stator d-q equivalent windings, are generated by two PI regulators controlling the two components-flux-generating and torque generating stator current. In the second scheme, the stator flux-oriented control method is used to control the torque of the induction motor. By using instantaneous voltage space vectors with selection of optimum inverter switching modes employing the vector modulation technique, the direct control of torque and stator flux is achieved.