High horse power ratings in AC drives by means of phase-redundancy technique-some experimental investigation

Phase-redundancy is a simple and unique technique for improving the reliability of large adjustable-frequency AC drives. As the name suggests, this technique is based on the inherent feature of a general n-phase AC motor to continue operation following loss of excitation to one or more of its many stator phases during open circuit or short circuit at stator terminals. This technique can, also be used to increase the horse power ratings of the machine in particular and AC drive systems in general, and the induction motor due to its simple and rugged construction is a perfect candidate for application of this technique. This paper, therefore, presents some experimental results conducted on a laboratory prototype to assess the increase in power rating under steady state condition. The results of this investigation are very promising and support the basic soundness of the phase-redundancy concept.