Research And Design Of Bridge Bi-directional DC Converter

In this dissertation, the bidirectional DC/DC converter was firstly investigated and studied which included the classification, current research and the trend of development. The study of bridge-typed structure was the focus. Then the Half-full bridge topology with neutral point clamped which was based on Dual Active Bridge structure was further investigated.Secondly, based on the traditional phase shift control, the variable duty cycle control was proposed. It was proved by the theatrical analysis and the simulation of static operation that this control method can extend the soft-switching range of the converter. Both forward and reverse transmission mode were included in the static operation simulation.Furthermore, a hardware and software design of a25kW,1200V-400V bridge-type bidirectional DC/DC converter was discussed. In the hardware design section, the selection of devices, the principle of key circuits, the design of heat-sink as well as the3D model simulation of the whole converter were covered. By selecting appropriate devices and the careful layout of the converter parts, the total size was comparably small and high power density was attained. The software design was based on the FPGA platform in which the design conception and verification waveforms were given as an example of phase shift control. In the software section, PI controller, sampling module, signal modulation and fault detection were discussed. For the PI controller module, a closed-loop simulation was implemented to find the parameters of the controller by observing the response curves.