Electric medium- and heavy-duty vehicles with elevated charging and auxiliary power requirements can benefit from three-port converters (TPCs) due to the reduction in magnetic size and device count. A topological analysis is the basis of this paper, wherein a TPC to interface a 890–1250 V HV battery pack and a 36–52 V auxiliary system is studied. A TPC with a current doubler (CD) is first explored in this work. A generalized harmonic approximation (GHA) based model for a TPC with a CD is outlined for a three-variable modulation scheme. A design optimization framework to determine feasible leakage inductances and turns ratios is used with control optimization for efficiency maximization. Comparisons are made to a conventional triple active bridge converter from which conclusions are drawn. A three-level neutral point clamped full-bridge (3L NPC FB) is then studied for the HV port. A six-variable control scheme is presented for the 3L NPC FB variant, along with the challenge of 1.7 kV SiC devices required in a conventional TAB for this application. A 25% reduction in cost and 0.45% improvement in time weighted average efficiency (TWAE) is noted for the variant with a 3L NPC FB.
