Functional Decomposition of a Medium Voltage DC Integrated Power System

The Navy recently produced a Next Generation Integrated Power System Technology Development Roadmap (NAVSEA 2007) that establishes the Navy’s goal of incorporating a Medium Voltage DC (MVDC) Integrated Power System (IPS) in future surface combatants and submarines. Some of the technical challenges in implementing a MVDC IPS include the requirement to develop new fault detection and isolation techniques; the establishment of design methods to ensure system stability with constant power loads; standardized methods for controlling prime movers and sharing loads between power generation modules; and a grounding strategy. This paper explores some of these challenges through a functional decomposition and allocation of those functions to different IPS modules. Several different functional allocations are proposed, compared and contrasted. For example, the functions of fault detection, fault location and fault isolation can be accomplished through the use of timecoordinated circuit breakers as is done in traditional a.c. systems (allocated entirely to the power distribution module), or can be accomplished through a combination of controls on the rectifiers of the power generation modules to limit current, fault location algorithms within the controls of the power distribution module, and controlled switches that are part of the distribution module. Each of these two functional allocations has impact on technology development, interface development, and design methodology. Based on the results of this analysis, recommendations for future architectural efforts in maturing MVDC IPS are presented