Hybrid Modulation-Based Discrete Extended-Phase-Shift Control for Dual-Active-Bridge DC-DC Converter
Jin Sha, Jinsong Shen, Han Bin Wang, Gaofeng Qiu, Yuebing Sun
Abstract
Aimed at the modulation and control of dual active bridge (DAB) dc–dc converter, a hybrid modulation method and the corresponding discrete control strategy are proposed to achieve fast and robust transient performance. The proposed hybrid modulation comprises extended phase-shift (EPS) modulation and multilevel pulse train (MPT) modulation, where MPT modulation serves to fast transient response across wide power range, while EPS modulation enables the minimum current stress optimization and dc-bias elimination. Then, a hybrid modulation-based multilevel discrete extended phase-shift (MD-EPS) control is designed. By introducing the load current to the proposed control, the instantaneous power of DAB dc–dc converter can be determined to realize the MPT-based control pulse generation, combined with logical judgment of the relationship between output voltage and reference voltage. To further improve the transient performance of the proposed MD-EPS control under significant load step change condition, both the outer phase-shift ratio and duty cycle of the secondary side switch control pulses are adjusted. The control principle, control parameter optimization method, and control performance are studied and validated using a 96-48 V, 50 kHz, 230WDAB dc–dc converter experimental platform.