Control of five-phase induction motor under open-circuit phase fault fed by fault tolerant VSI

Abstract

Five-phase induction motor drive systems have gained much popularity due to the numerous advantages that they offer when compared to their three-phase counterparts. In principle, the supply to five-phase drive system is given from five-phase voltage source inverter (VSI). In this paper, a fault-tolerant control strategy for five-phase VSIs has been suggested. The conventional five-phase inverter consists of only five legs. The proposed strategy forces the faulty phase to connect to the midpoint of the DC-link via the additional dc-bus midpoint inserting Thyristors. The proposed inverter provides tolerance to both short-circuit and open-circuit faults of the switching devices. The performances of the post-fault as well as the normal pre-fault operation are discussed. The fault tolerance of the inverter is verified using vector control of a five-phase induction motor. The complete control scheme is implemented in real-time using digital signal processor (DS1104) for a prototype 1.5 hp motor. Experimental results of the proposed drive verify the proposed control scheme.