Analysis and implementation of a new method to retain the original speed and torque of synchronous reluctance motor during sustained voltage dip

摘要

This study presents the operation of a synchronous reluctance motor drive under a sustained voltage dip condition while being connected to a weak grid. In the presence of an input voltage dip, motor may not be able to produce sufficient torque and maintain its original speed. A new technique is proposed in this study to maintain the desired reference torque and speed during a sustained voltage dip. The proposed technique is realised by evaluating mathematically the motor's allowable voltage dip margin corresponding to an operating point pertaining to a particular torque and speed in the current locus diagram of the motor. With prior knowledge of the voltage dip margin for every operating point in the current locus diagram, it would be possible to retain the same reference torque and speed by moving to a new operating point, which can be with lesser or greater id as compared to the initial operating point, in case a voltage dip greater than the tolerable margin occurs. To start with, voltage dip margin has been derived theoretically and the operation of the motor is investigated by deliberately introducing a voltage dip. The proposed methodology has been verified through simulations and experiments in this study.