Research On Control Technology Of The Bi-directional Full Bridge DC/DC Converter

With the development of science and technology and the application of new energy,the bi-directional DC-DC converter has been widely applied in the fields of the solarenergy generating systems, aero power-supply system, DC unremitting power sourcesystem, energy management system of electric vehicle, and so on. Especially in the use ofindependent photovoltaic system, the bi-directional DC-DC converter can realizebi-directional transfer energy between the DC bus and the energy storage unit. This paperselected the bi-directional full bridge DC-DC converter as the object of study andconcentrated on the research of the phase-shift control strategy for bi-directional fullbridge DC-DC converter.In the traditional phase-shift control strategy for bi-directional full bridge DC/DCconverter, the backflow power problem exists which leads to reducing the efficiency of theconverter, increasing the current stress and reducing the range of soft-switching. And it’sfar more serious when the there is mismatching between input voltage and output voltage.On this basis this paper proposes a new phase-shift control strategy, the bi-directional fullbridge DC/DC converter with dual-phase-shifting control method which can reduce thepower circulating flow, achieve the maximum transmission of the power and soft-switch.The operation principle of the dual-phase-shifting control has been analyzed in this paperand the dynamic models of the converter were constructed contemporary. We can obtainthat the dual-phase-shifting control method can enhance the flexibility of the powercontrol ranges. And by contrast with the range of soft-switching of the traditionalphase-shift control strategy, the dual-phase-shifting control method is easier to achieve thesoft-switching. And then the theory was verified by the simulation of MATLAB.At last, according to the requirement of the subject, the experimental platform forbi-directional full bridge DC-DC converter has been designed based on the digital controlcore of DSP28027to verify the theoretical analysis. This paper proposed the directgeneration method of digital phase-shifting based DSP which can conveniently generatethe shift-pulses and set the dead-time.