HIGH-PERFORMANCE SPEED CONTROLLER FOR VOLTAGE-SOURCE INVERTER-FED INDUCTION-MOTOR DRIVES

An LMFC system with variable-control law for voltage-source inverter-fed induction motor drives 'is proposed. The drive system is implemented, and an estimation technique is developed to find its dynamic model from the measured-step rotor speed response. In the proposed controller, the plant is approximated by two reduced submodels with very low orders, which are found to give good approximations in the initial transient and the static periods. The fast and slow control laws are then designed according to the selected reference model and the submodels. A switching mechanism is used to select the control law for the plant. Only the information on the reference model and the plant output is needed for the control; it is thus easy to implement. The orders of the reference model and the control law can be minimised, and good control performance in the whole period can be obtained. The simulation and measured results are provided to demonstrate the effectiveness of the proposed controller.