Research On Digital Controlled Phase-Shift Full Bridge DC-DC Converter

In order to decreases the volume and the weight of Switching Mode Power Supply(SMPS) ,the power switches work into the state of quickly turn on and quickly turn off switching mode .this mode can bring the disadvantage of the switching losses of the power switches. The principle of the soft switching is presented to solve this problem. Zero Switching PWM(ZSPWM) technique is one of soft switching technique. There are two kind of Zero Switching PWM(ZSPWM) techniques: one is the Zero Voltage Switching(ZVS), the other is Zero Current Switching(ZCS).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. The resonates creates the state of the soft switching. A resonant inductance and two clamping diodes can be introduced to the primary side in order to eliminate the voltage oscillation caused by the reverse of the rectifier diodes. In this paper ,this topology is presented. The principle of this topology realizing ZVS is discussed. The waveform is presented too. There is also a brief introductions of the others topology of ZVS and ZVSZCS. The disadvantage and the advantage of the topology is showed in the end of the chapters . In traditional, the control methods of the ZVSPWM topology is the analog control . A digital control circuit use DSP(digital signal processor) is showed in this paper. A new methods of using DSP create shifting pulse is showed in the paper. The method has the advantage of the simple, direct, and realize easily. The shift pulse created by the method is precision. The digital control method is the soul of the digital control system. Comparing with the analog control ,digital control has the advantage of the variability compensate for the disadvantage of the effects of finity length effect, delay. In this paper ,a new control method combine PI controller with Bang-Bang controller is discussed. In the end ,the waveform of the performance of the designed machine is presented. The conclusion can be getting finally.