Reliability assessment of fault tolerant permanent magnet AC drives

Reliability of electric drives is of paramount importance for safety critical applications in transportation, medical and military industries. While numerous fault tolerant machine and inverter topologies have been developed for improving drive reliability, comprehensive reliability evaluation of fault tolerant electric drive systems has not been reported in literature. This paper performs quantitative assessment of mean-time-to-failure of representative fault tolerant permanent magnet AC drive systems by employing Markov chain modelling technique. It is shown that the mean-time-to-failure of a fault-tolerant drive can be significantly increased by employing health monitoring/maintenance check and prompt repair/replacement of faulty components.