Nonlinear voltage regulation of an auxiliary energy storage of a multiport interconnection

Abstract

Motivated by the explosive increase in the use of DC–DC converters due to the massification of renewable energies, in this article we propose a nonlinear voltage control to ensure power exchange in a multiport interconnected system, which consists of a bidirectional DC–DC converter and generating-storing devices. The converter topology under consideration is two-stage, composed of an interconnection of a buck with a boost converter. The control design for this system does not correspond to that in standard applications involving power converters. As it is known, the latter consists of finding a control law such that the closed-loop system has an asymptotically stable equilibrium point fulfilling the voltage regulation objectives. Instead, in this application, the state does not tend to an equilibrium value in order for the system to be regulated. The converter voltage is regulated at some desired setpoint whereas the other variables are only required to be bounded. To achieve a dynamic response that best adapts to changes in system demand and ensure stability over the defined wide operating range, we propose a novel control strategy that exploits the partially cascaded structure of the system. Experimental results validate our approach.