Passivity-based nonlinear control for an isolated microgrid system is proposed in this paper. The microgrid consists of a photovoltaic array and a battery energy storage connected to a point of common converters, supplying a constant power load. The purpose of this control strategy is to maintain the output direct current voltage in its reference value under load variations, improving battery interaction. The system is represented by its state space averaged model and the proposed controller is designed using the interconnection and damping assignment strategy, which allows obtaining controller parameters while ensuring the closed-loop system stability. The unknown constant power load is estimated using an observer based on the energy function of the system. The behavior of the proposed control strategy is validated with simulation and experimental results.

This article presents a novel nonlinear control strategy for an active triple-bridge converter used in a direct current (DC) microgrid with multiple buses to interconnect its three constituent buses, which are comprised of generation systems and generalized loads. The proposed controller aims to regulate the voltage on two of the DC buses and manage the power exchanged between them in response to load and voltage changes. Unlike the existing literature, the control strategy is designed based on the generalized state-space averaged model of the converter, obtained from the delta equivalent circuit of the high-frequency transformer. The performance of the designed controller is validated through simulation results, demonstrating good performance under changes in generated power, load variations, and voltage fluctuations on both DC buses of the microgrid.