H∞Technique-Based Robust Controller for Buck DC/DC Converter Loaded by Constant Power Load in DC Microgrids

فاقد چكيده فارسي

Multi-converter DC distributed power system (DPS) is widely used in DC microgrids. The configuration of such systems often consists of many switching DC/DC converters, which loaded by other converters. In such interconnected systems, the cascaded connection of the source converter with its load-side counterpart is a prevailing connection form. When the load converter regulates its output tightly, it acts as a constant power load (CPL) for its source converter. CPLs exhibit negative incremental resistance and thus, tend to destabilize the system. Moreover, factors such as variations of input voltage and load as well as the system’s parameter uncertainties can adversely affect the system stability. Hence, to achieve robust and safe performance in these systems, the stability issue and the guarantee of a constant output voltage in the presence of the aforementioned destabilizing effects, are of great importance. To realize this goal, this paper designs an H∞technique-based robust controller for a cascaded DC DPS consisting of a buck converter operating in continuous conduction mode and loaded by a CPL taking into account the considerable variations of input voltage and load as well as the system’s parameter uncertainties. To that end, a small-signal transfer function of DC-DC buck converter feeding a CPL is firstly derived from the system via the averaged state-space modeling. Then, by using the unstructured uncertainty modeling approach, all the uncertainties and perturbations considered are added for developing the controller model. System Model and controller design are explained in detail and simulation results are provided to demonstrate the effectiveness and robustness of the proposed control method against uncertainties.