Study On Key Technologies Of High-power PSFB Power Supply With Synchronous Rectifier

In recent years,high-power switching power supply in the industrial production has become increasingly widespread,such as non-ferrous smelting,electrolytic plating,high-frequency heating and so on.These industries consume a large number of electricity,even if the power efficiency is only increased by 1%,which can also bring huge economic benefits.Traditional high-power switching power supply using diode rectifier,in the high current output conditions,the conduction voltage drop will bring huge losses,seriously restricting the power level and efficiency of the upgrade.Synchronous rectification uses MOSFETs with very low on-state resistors replacing diode rectifier,which can reduce the rectifier losses and improve power efficiency.It is a very useful engineering technology.At present,most of the hotspots of synchronous rectification research are in low power applications,while they are not mature enough in high power applications.Based on this,this paper has made a study on the application of synchronous rectification technology in high power switching power supply.First of all,this paper studies the basic principle of phase-shifted full-bridge synchronous rectification circuit from two aspects.The one is to study the operation mode of the phase-shifted full-bridge synchronous rectification circuit.The other is to study the mathematical model by the three-terminal PWM switch model and give the small signal circuit and transfer function.Based on this,a closed-loop design of the system is made.Then,the application of synchronous rectification side is studied in this paper.First,the problem of synchronous rectification side loss optimization is studied from three aspects:MOSFET loss model,low power loss analysis,high power loss analysis.Second,the synchronous rectifier side parallel current is studied.The factors influencing the parallel current sharing of the MOSFET and the influence of the original secondary structure on the current sharing of the transformer are studied emphatically.Some suggestions are made to improve the current sharing.Then,this paper makes a detailed analysis on the development of high-power phase-shifted full-bridge synchronous rectification power supply system.Finally,a 2800A/15V high-power phase-shifted full-bridge synchronous rectified switching power supply is developed based on the previous analysis,and the stability and high efficiency of the power supply are verified by experiments.