Short-Horizon Finite-State Voltage Control of Bidirectional DC–DC Converter with Non-Minimum Phase Dynamics

Bidirectional DC–DC converters play a critical role in DC microgrids by enabling regulated voltage conversion and bidirectional power flow between energy sources, storage systems and loads. However, achieving fast and robust voltage regulation in such converters remains challenging due to non-minimum phase (NMP) dynamics, digital implementation delays and model uncertainty. In the literature, short-horizon finite-state voltage control strategies are presented as desired methods for controlling these converters. In this paper, a systematic comparison of recent short-horizon finite-state control strategies—including single-horizon finite-set model predictive control (FS-MPC), compensated bang-bang (BB) control and BB control with doubled sampling frequency (DSF-BB)—is first presented. Subsequently, a novel model-free bang-bang (MF-BB) control strategy is proposed. The proposed model-free approach eliminates reliance on an explicit system model by generating the desired inductor-current reference directly from measured current signals, while preserving short-horizon operation and low computational complexity. The performance of the proposed method is then compared with existing approaches through comprehensive simulation studies under non-minimum phase operation and digital implementation delays. Additional evaluations consider parameter variations and conduction-mode transitions. The simulation and experimental results demonstrate that the proposed MF-BB strategy achieves transient response, settling time and steady-state voltage regulation comparable to the model-based methods while eliminating dependence on converter parameter accuracy. These findings highlight the effectiveness and practical suitability of the proposed approach for digitally controlled bidirectional DC–DC converters in DC microgrid applications.