Synergetic Control Strategies for Shipboard DC Power Distribution Systems

This paper presents a synergetic control design for a generalized component of modern ship DC distribution systems such as an arbitrary number of paralleled buck converters feeding a constant power load. The design uses a state space averaged model of the system and overcomes the system´s nonlinearity, multi-connectivity, and high dynamic order, which are challenging features for control development. The design results in general analytical control strategies, conditions for counterweighing the system´s nonlinearity, and stability conditions for the closed-loop operation. The control introduces invariant manifolds into the state space of the system and suppresses errors in output voltage and current sharing. The coefficients of invariant manifolds allow us not only to counterweigh nonlinearity and allocate the type and ratings of current sharing for each converter, but also allow to change the number of operating converters. The control strategies are first applied to a two-converter system to demonstrate how the designed control dynamically allocates the current sharing within the system. Next, a two-converter system under synergetic control and feedback linearization control shows superiority of synergetic control performance. Finally, an eight-converter system presents a coordinative control strategy that optimizes the system´s efficiency by changing the number of operating converters.