Modern DC power systems consist of a large number of power electronic converters and associated
equipment. On a ship, this power system is typically divided into two identical parts on the port and
starboard sides. These duplicated power systems are often isolated from each other to prevent a fault on one side from propagating to the other side and affecting the entire system, avoiding a total blackout on the ship. A major drawback of this two-split configuration, though, is that it is impossible to share power between both sides, reducing the functionality of the system. Therefore, to connect both sides while maintaining the safety of an isolated system, a solid-state circuit breaker (SSCB) can be used, which is reusable, unlike a fuse, and is able to interrupt the current much faster than a standard mechanical circuit breaker. However, due to the relative novelty of this component, the impact of mission profile variation and electrical disturbance on the SSCB lifetime is unknown.

To obtain the SSCB lifetime, mission profile analysis was performed, resulting in a lifetime as a consequence of wear-out failure mechanisms due to thermomechanical fatigue that would be used as the base case. Based on the mission profile, an SSCB model was designed following considerations for: Current interrupter topology, rated voltage/current of the components, peak voltage/current of the components, voltage clamping circuit, and the cooling. After choosing suitable components, their junction temperature profiles were obtained via iterative calculations with the power loss and the junction temperature using a Cauer model without thermal capacitance. With the rainflow counting algorithm, information regarding the cycle count, temperature swing, mean temperature, minimum temperature and the power-on-time per class was obtained. These were used in the CIPS with correction lifetime model, which obtained the cycle-to-failure of each relevant component. Transforming them into a reliability curve per component and multiplying them together resulted in the reliability curve of the SSCB. To estimate the impact on the lifetime of the electrical noise through the SSCB in comparison to the mission profile, a dynamic model was designed to take thermal capacitance into account, unlike the iterative model.

To quantify the impact of different stressors on the SSCB lifetime, changes in the mission profile, SSCB configuration and operational parameters compared to the base case are made. It was seen that the charging current, corresponding to changes in the maximum stress within the mission profile, has the most significant impact on the SSCB lifetime, while having a relatively minor drawback of a varying charging period. Bi-directional charging and changes in the coolant temperature were shown to have a relatively low impact on the lifetime. Load sharing between parallel components in a module significantly increased the lifetime, but at a cost of practically investing in a second SSCB. Concerning the impact of noise on SSCB lifetime with respect to the damage done by the mission profile, it can be concluded that high-frequency noise, such as the common-mode and differential-mode noise, has a negligible effect on the lifetime of the SSCB when solely focusing on wear-out mechanisms due to thermomechanical fatigue.