Research On Phase-Shift Full-Bridge ZVZCS DC/DC Converter Based On DSP

Soft-switching technique is a hotspot of power electronic research. It's the key technique in the high frequency and high-density converter. With the advent of microprocessor, there has been an increased interest in digital control of switch mode power supply, instead of analog control. The digital control scheme has many advantages in simplifying the control circuit, improving the anti-interference ability, control precision and flexibility, general and intelligent level.Full bridge shift phase soft switch topologic circuit is extensively applied topologic structure in high power and high frequent switch power system. In this thesis, the power switching realize ZVS or ZCS with the resonates between the leakage inductance of the transformer or extra inductance and the intrinsic capacitors of the power switches or extra parallel capacitors, therefore it can avoid high current and high voltage occur at the same time and greatly decrease electronic unit switch loss.In order to reach both high frequency and digitalization of converter, a phase-shifted full-bridge ZVZCS Converter based on DSP control is proposed in this thesis. First of all, the study background, direction and main content of this thesis are presented. Based on the analysis of the characteristics with three kinds of phase-shifted full-bridge soft switch topologic circuits and the operation of phase-shifted full-bridge ZVZCS DC/DC Converter, the main circuit, the driving circuit, the sampling circuit, the protecting circuits and the auxiliary power supply circuits are designed. The method of component parameter design and the design flow of magnetic components such as transformer are also presented. In addition, the simulation analysis of the main circuit is carried out by the OrCAD10.5/PSpice software. The topology selected is proved to realize ZVZCS easily. To improve system performance, the double loop control model with an inner current-loop and an outer voltage-loop and duty-cycle loss taken into account is deduced on the small-signal model analysis of this topology; and the parameters of PI regulator is designed for the current-loop and voltage-loop. The simulation analysis of control system is also carried out by the MATLAB6.5 software. Double loop control with average current mode is proved to solve the conflict between stability and dynamic performance.At last, a creating shifting pulse scheme based on DSP is showed and particular software design and program flow charts are also given.