Bounded finite-step voltage control of dual-active-bridge converters with constrained triple-phase-shift modulation

Purpose This study aims to improve transient voltage regulation of dual-active-bridge (DAB) converters operating under fast and highly dynamic load conditions, such as those encountered in artificial intelligence (AI) data-center power delivery systems. Conventional voltage-control approaches often struggle to coordinate voltage recovery, current stress and zero-voltage-switching (ZVS) requirements simultaneously. Therefore, a bounded finite-step voltage control (BFSVC) strategy combined with constrained triple-phase-shift (TPS) modulation is proposed to achieve rapid voltage recovery while maintaining physically admissible ac-link current trajectories and preserving switching reliability. Design/methodology/approach A bounded finite-step voltage controller is developed based on output-capacitor charge balance and load-current estimation. The controller generates a slew-limited power command using capacitor-current compensation, load feedforward and voltage feedback. A constraint-based TPS/single-phase-shift (SPS) allocation mechanism is then used to select feasible modulation commands according to average-power tracking accuracy, ac-link current limits, ZVS-current reserve, endpoint-current consistency and pulse-width constraints. The proposed method is validated through switching-cycle simulations and experiments on a 5 kW DAB prototype under nominal load steps, burst-load profiles, low-input conditions and constant-power-load scenarios. Findings The proposed BFSVC strategy effectively improves transient performance while preserving switching-cycle constraints. Compared with conventional SPS plus PI control, it reduces the maximum voltage error by 42.9% under low-input conditions and decreases endpoint-current mismatch by up to 70.2%. During burst-load operation, the minimum ZVS-current margin is significantly enhanced, improving switching robustness. Experimental results demonstrate stable bus-voltage recovery and repeatable leakage-current trajectories under large load disturbances. The findings confirm that fast voltage recovery can be achieved through bounded power commands without sacrificing current-stress management or ZVS operating margins. Originality/value The originality of this work lies in the integration of finite-step voltage control with a constraint-driven TPS/single-phase-shift (SPS) modulation allocator. Unlike conventional voltage-loop designs that focus primarily on voltage regulation, the proposed framework explicitly incorporates current stress, ZVS reserve, endpoint-current consistency and modulation feasibility into the control process. The study establishes a practical separation between voltage-command generation and modulation allocation, enabling fast transient response while maintaining switching-cycle admissibility. This approach provides a systematic and implementation-oriented solution for high-voltage, high-power DAB converters serving rapidly varying loads in next-generation data-center applications.