| In recent years, the industrial demands for bidirectional DC-DC converters has increased day by day, such as power supply for electric vehicles, uninterruptible power supplies(UPS), aircraft power system and solar power supply system. In other hand, high-power and high power density bidirectional DC-DC converter has been one of hot topics because of the demand for energy bidirectional conversion. The traditional bidirectional DC-DC converter only suits to low and medium-power applications, however, the problems that both voltage stress and switching loss for switches are great will appear when used in high power applications. In this background, high-frequency DC-DC converter with higher boost voltage conversion ratio and reduced peak switch voltage stresses are particularly required for adapting to the development.First of all, in this paper, the basic topological structure, principle and application of bidirectional converter are discussed, several kind of soft switching bidirectional converter are given. The disadvantages of small boost voltage conversion ratio and large switch voltage stresses are analyzed.In order to solve the practical problem effectively, a novel bidirectional DC-DC converter based on coupling inductor, the traditional isolated booster circuit transformer is replaced by coupling inductor in this converter proposed, which decreases the volume of converter, gains a high boost voltage conversion ratio and reduces the peak switch voltage. And then the operating principle of the novel bidirectional DC-DC converter and the dynamic process in mathematical are analyzed. And the relation between theoretical boost voltage conversion ratio and the peak switch voltage are given which is verified by the simulation. Several other kinds of bidirectional converter based on coupling inductor are also given.In order to decrease the switching loss of converter, an active clamped soft switching cell is introduced to the bidirectional DC-DC converter based on coupling inductor mentioned previously, then the soft-switching operational principle and mathematical expression analysis for the dynamic process of each mode are given. The soft switching implementation condition is deduced, voltage and current stress of the converter are calculated, simulation parameters are designed. The excellent soft switching characteristic and theoretical analyzing correctness of this converter are verified by the computer simulation with MATLAB under different conditions of load current and duty cycle.Finally, both the hard switching and soft switching bidirectional DC-DC converter based on coupling inductor are compared under the boost model in this paper, and the superiority of soft switching is proved. |
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