A Comprehensive Optimization Control of Dual-Active-Bridge DC–DC Converters Based on Unified-Phase-Shift and Power-Balancing Scheme

This paper presents a comprehensive optimization control scheme to improve efficiency and dynamic response of dual-active-bridge (DAB) dc-dc converters. Unified-phase-shift (UPS) control is widely used to increase the efficiency of DAB dc-dc converters by minimizing the peak current, but dynamic performance of the converters needs to be further enhanced. In this paper, to gain superior dynamic performance of DAB dc-dc converters, an equivalent power-balancing (PB) model is employed, which is capable of predicting dynamic behavior of converter output voltages due to input voltage fluctuation and load disturbance. And then, combining the UPS control and the PB control, a comprehensive UPS and PB (UPS-PB) scheme is proposed to improve the efficiency and dynamic performance simultaneously. This work also includes the detailed inductance parameter sensitivity of the proposed UPS-PB scheme and a zonal voltage control strategy to further improve dynamic responses of the output voltage under the start-up process or a large step change of the output voltage reference. Moreover, the variant of UPS-PB scheme for constant power load is analyzed in the experimental part. Finally, experimental results have verified the excellent performance of the proposed UPS-PB scheme and correctness of theoretical analysis in this work.