A Research And Design Of Sysnchronous Rectifier In High-Power,High-Frenquency Switching Power Supply

Electric power is the essential power source for power equipments and electronic equipments. Switched-mode power supply has many significant advantages, such as high efficiency, low power consumption, small volume and light quality, etc. Its power efficiency can reach over80%, which is much higher than that of the linear power. Switched-mode power supply has a broad development prospect and a wide range of application. It is the future direction of the power supply design and production and also the mainstream of current research on high power supply. It can be widely applied to lots of industries, including industrial equipments like power plant excitation, and civil communications, computer, household appliances and transport facilities, etc. These applications have some common requirement for power supply—high current and high output power. However, as it works always under high current, which causes particularly serious loss to the equipment, hence, it is a key and difficult point for the rectifier to improve its working efficiency.To settle this problem, this paper starts from introducing the development of high-power switching-mode power supply and its topology and adopts the most appropriate high-power switching power supply topology by analyzing different kinds of topological structures of DC—DC conversion in the switching power supply with isolated transformers. Based upon this, it studies the synchronous rectifier technology used in the switching-mode power supply and analyzes the high-power switching power supply circuit operation principle and operation method by combining with the phase shifting full bridge soft switch technology (PS-ZVS). According to the analysis of the characteristics of high-power switching power supply and circuit, it calculates the parameter of the major part of power source and thus selects suitable circuit components and then provides some calculation methods of voltage and current in the vice edge, capacitance and inductance in output side storage filter.Meanwhile, this paper proposes a control platform with new control architecture through studying the control mode of switching power supply based on the technology of synchronous rectifier and designs a core control board dominated by chip UC3879by adopting the phase shift PWM soft switch control chip UC3879and complex programmable logic device FPGA collaborative control. It also selects a specified drive control chip and designs a special driving circuit for power devices by virtue of studying the drive circuit of power switch tube; moreover, it successfully accomplished the control of secondary synchronous rectifier signal, PI regulator as well as the synthesis and control of other signals by employing verilog HDL hardware language to write the FPGA control procedures.Finally, this paper designs a high efficient High-Power Phase-Shift Full Bridge Zero Voltage Switch Synchronous Rectifier (PSPB-ZVS-SR) used as the experimental prototype system, which is proved to be with the characteristics of high power and high efficiency through experimental waveforms provided in the practical testing.