| High power DC-DC converter was a main part of power electronic converter. Inorder to reduce the volume of converter, decrease the switching loss of powerdevices and improve the efficiency of the converter, soft switching technology playsan important role in improving the frequency and the power density of the powerelectronic device. With the rapid development of the microprocessor, a powerelectronic converter was brought to the digital control field from traditional analogcontrol method. The detailed analysis of the soft-switching and digital controltechnique, and the key problems of the PS-FB-ZVS converter were proposed, thesimulations and experiments were also given.Firstly, several common soft switching technology of the phase-shift full-bridgeDC-DC converter were compared and analyzed in this dissertation. According to theparameters characteristics of the DC-DC converter that the project designed, thezero-voltage switch was chosen as the soft switching mode, the working principle ofthe circuit of the phase-shift full-bridge ZVS soft switching was analyzed, and thezero voltage switching characteristic of the lead leg and lag leg of the converter werestudied.Secondly, according to the analysis of the soft switching characteristics, theparameters value of the main power devices of converter were calculated. Based onthe designed circurt parameters, the simulation model of the converter wasestablished by MATLAB software. The rectifier and filter circuit, the driving circuit,the sampling circuit, the auxiliary power supply circuit, the protecting circuit andother main circuit were designed.Finally, the chip characteristic of DSP TMS320F2812in digital control systemwas introduced. The control chip how to make full use of its function modulesproduce phase-shift control drive waveform was especially focused on. According tooperational process of the control system, the main program flow chart, interrupt subprogram were designed. To prove the correctness of the selective scheme, a lot ofexperiment on experimental model machine was done and the result of experimentwas analyzed. |
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