Reliability assessment of an autonomous underwater vehicle propulsion by using electrical multi-phase drive

This paper investigates the reliability of 3-phase, 2×3-phase and 5-phase inverters for a marine propulsion application. Analytical formulae and thermal model are used to assess the junction temperature of the semiconductors. The overall failure rate of the inverter is calculated by using the individual failure rate of each semiconductor, which depends on its junction temperature. In case of open-phase fault, state transition diagrams show the reconfiguration capabilities and Markov models are used to quantify the reliability improvement of 5-phase system with respect to 2 × 3-phase and 3-phase systems. This enhancement obtained by changing the current control strategy makes the motor to operate with reduced but sufficient performances.