Modeling and Dynamic Control of a Three-Phase Dual-Active Bridge Converter Using a Hybrid Modulation Scheme

This paper presents the modeling and control method of a three-phase dual-active bridge (DAB3) converter using a hybrid modulation scheme, which combines the single-phase-shift modulation (SPS) and the asymmetrical duty-cycle control (ADCC) to improve the partial-load efficiency. The small-signal models of the DAB3 converter under different modulation schemes are obtained using the state-space averaging technique. Thereby, a unified closed-loop controller is designed for the hybrid modulation scheme in the frequency domain. Seamless mode transition is achieved by the proposed mode selection algorithm. To improve the dynamic performance during mode transition between SPS and ADCC, the hybrid-mode instantaneous current control is proposed which can reduce the current overshoot effectively. The proposed control is validated by simulations and experiments on a scaled-down laboratory prototype.