Fault-tolerant PM brushless DC drive for aerospace application

Reliability is a fundamental requirement in airborne equipments, it involves a particular approach of study on mission failure probabilities. Architectures robust to failure of single components like multi-phase fault-tolerant motors drives introduce in these systems an intrinsic improvement. By providing compensation for potential hardware failures, a fault-tolerant design approach may achieve reliability objectives without recourse to non-optimized redundancy or over-sizing. A fault-tolerant design approach differs from a pure design redundancy approach in that provisions are made for planned degraded modes of operation where acceptable. This study shows how a 5-phase motor is able to run at rated torque also with one or two phase open, by using suitable current commands defined as degraded modes. An experimental prototype has been arranged and tested.