Lifetime and Cost Analysis of DC-DC Solid State Transformers for Wind Applications

Lifetime assessment of high-power solid state transformer (SST) is a challenging task due to many factors affecting their lifespan. High-power SSTs are more complex than their low-power counterparts since more components are required in their design. This adds another challenge to the lifetime assessment. In the literature, SSTs are studied but their lifetime assessment is not covered. Moreover, the relationship between lifetime and converter cost is missing. This paper investigates the lifetime and material cost properties of modular SiC MOSFET-based DC/DC SSTs for offshore wind farm applications. The variation in cost and lifetime is investigated based on four different design variables. These four design variables are the submodule topology of the SST, the number of parallel semiconductor switches, the high blocking voltage of semiconductor switches, and the cooling type of the SST. Comparative results indicate that the best lifetime and cost results are obtained utilizing a dual-active half-bridge (DAHB) topology, a single semiconductor switch in parallel, a 2000 V switch operating voltage, and forced air cooling.