Design On The Phase Shifting Full Bridge With Current Double And Synchronous Rectifier

With the rapid development of information technology, the low-voltage high-current converter has been widely used in computer, communications and other fields. Now most of low-voltage high-current converter using isolation BUCK converter, in order to reduce the loss of converter input DC bus and reduce the volume of input filter, the input voltage of the converter is constantly improving, and the output of the transformer voltage is lower and output current is bigger, constantly improve the switch frequency, so traditional BUCK converter cannot meet the requirements of low-voltage high-current converter.Based on the basis of the development of low-voltage high-current converter both at home and abroad, through the comparison of several kinds of typical main circuit topology selection, the full bridge current double synchronous rectifier circuit being the main circuit topology is established, and its working principle and working mode has been made the theoretical analysis. In low-voltage high-current output, the synchronous rectifier technology can be made up for the loss of the traditional diode rectifier big shortcomings, and realize the high efficiency DC- DC transform. Because of the two output crisscross parallel inductance, the current double rectification technology, can effectively restrain the output current ripple, and reducing the size of the inductance. At present, the study of the full bridge converter mostly adopts the phase shifting control technology, so the paper adopts the phase shifting control technology, and use the leakage inductance of the transformer with the junction capacitance switching device to achieve full bridge soft switch of switching tube, which being reduced the switching loss of switch tube, and further improving the efficiency of the converter. The article uses the voltage closed loop control, in order to improve the stability of the converter.UC2875 is a phase shift resonant controller and its control way completely conform the requirements of full bridge current double synchronous rectifier soft switch converter.HIP4081 is a high frequency bridge FET driver, which have four road with isolated drive pulse output. This article uses UC2875 and HIP4081 to achieve the phase shift control of main circuit, which gives the main switch devices to realize ZVS of the specific conditions and parameters design, and the main circuit and control method of converter, transformer design, and using PSPICE simulation software for the simulation of converter system validation, so the simulation results are consistent with theoretical analysis.Finally, this paper based on the theory above, successfully designs a converter which input is between 36 V and 60 V, and switching frequency is 100 KHZ, and output is 3.3V, and the current between 0 and 15 A.The results of experiment can satisfy the requirements of design index, so the correctness of the theoretical analysis is verified by experiment.