Research Of Isolated Bidirectional Full-bridge DC-DC Converter With Novel Modulation Strategy

This paper mainly addresses different kinds of phase-shift control of isolated bidirectional full-bridge DC-DC (IBDC)converter, and finally proposes a novel single-phase-shift (NSPS) control and the optimal modulation strategy(OMS) based on NSPS control as well as dual modulation strategy(DMS). Firstly, an overall study of power characterization of IBDC converter in conventional single-phase-shift (CSPS)control was presented, the soft-switching region and deadband compensation in wide voltage ratio range was researched, also the pricinple of system design was proposed, the simulation and experimental results validate the correctness of theoretical analysis. To solve the drawbacks of CSPS control, for instance, high current stress and reactive power, the dual-phase-shift control was analysed, and optimal trajectory of DPS control was obtained and verified by experiments. As DPS control is complex to implement in engineering and it is difficult to realize close-loop control, this paper proposes NSPS control, and a complete theory of NSPS control is presented. Based on mathematical models in steady-state condition, this paper gives an overall study of power characterization in NSPS control and CSPS control in wide voltage raito range, including of reactive powr, backflow power and current stress. To ensure excellent performance in the whole voltage range, this paper proposes the OMS control based on NSPS control According to different voltage ratio range, which can decrease the current stress, reactive power and backflow power dramatically compared with CSPS control. Meanwhile, in comparision with DPS control, the OMS control has amolst similar performance with DPS control while OMS control is as easy as CSPS control to implement. Besides, while the output power beyond power range of OMS control, this paper proposes dual modulation strategy (DMS) to ensure the whole range of output power. Finally, a series of experimental results validate correctness of NSPS control and OMS control, the experimental results show that the OMS control can significantly decrease the current stress and reactive power in whole voltage ratio range, also the soft-switching regions are extended, the system loss are dramatically reduced, the efficiency of IBDC converter can be enhanced as high as30%.