Post-fault control strategy of rotor field-oriented induction motor drive fed from cascaded H-bridge multi-level converter

Abstract

In this paper, a control technique is proposed to maintain the torque and speed of the rotor field oriented induction motor (RFOIM) fed from a cascaded H-bridge multi-level converter (CHB-MLC) in post-fault operation. In this post-fault control technique, a common mode voltage (CMV) is added to the reference phase voltages according to the motor's loading condition and the converter's fault configuration. The addition of this CMV ensures that the amount of power generated in each phase is proportional to the number of remaining healthy cells in that phase. Moreover, maximum line voltage is also obtained in the post-fault operating condition. The mathematical expression of the CMV to be added in post-fault operation for equal power sharing among the remaining healthy cells and the analysis of motor's operating point are derived and explained. Computer simulation and experimental results are presented to validate the proposed control technique.