Lifetime Assessment of Power Electronics for Propulsion and Charging in Marine Leisure Vessels with Boat-to-Grid Capability

This paper presents a lifetime assessment of a marine leisure vessel propulsion and charging architecture comprising Dual Active Bridge (DAB) converters and a threelevel Neutral Point Clamped (NPC) inverter with Boat-to-Grid (B2G) capability. Analytical lifetime models, combined with thermal-electrical simulations and realistic operating profiles, are used to estimate the durability of semiconductors, capacitors and transformers under varying cycling frequencies, power levels, and temperatures. Results for the base-case scenario ($\mathbf{4 0}$ drive-cycle operation days and 220 B2G days at two cycles/day) indicate lifetimes of $\mathbf{1 0. 7}$ years for DAB SiC MOSFETs and $\mathbf{9. 7}$ years for NPC DC-side IGBTs, with passive components exceeding 13 years. Parametric studies reveal that increasing daily cycles from 2 to 6 reduces converter lifetimes to 3.6 years (DAB) and 3.2 years (NPC), while halving power can extend lifetimes by up to $200 \%$ and $50 \%$, respectively. Passive component life decreases sharply with temperature, with transformers more sensitive than capacitors. The findings underscore the importance of thermal management, lifetime-aware B2G scheduling, and power optimization to align component life with vessel design targets.