Voltage Oscillations Stabilization in DC Microgrids: A Strategy Using Improved Model Predictive Control

Tightly regulated point-of-load (POL) converters behave as a constant power load (CPL) within their control bandwidth, exhibiting incremental negative input impedance (NII). Due to NII characteristics, the POL converter tends to destabilize the system and may cause low-frequency voltage oscillations across the input dc capacitor of the POL converter. To address these challenges, this article proposes an active damping stabilization control. The proposed approach incorporates a stabilization term into the cost function (CF) of the finite control set model predictive control (FCS-MPC) algorithm utilized for POL converter regulation. By integrating a dc-side control CF in FCS-MPC, the proposed scheme significantly improves transient response and effectively dampens low-voltage oscillations across the input dc capacitor without compromising ac voltage regulation. Moreover, the implementation of this method requires fewer current sensors as compared to alternative approaches. Simulation and experimental results demonstrate the effectiveness and robustness of the proposed active damping stabilization control, validating its potential as a valuable solution in POL converter applications.