The Design Of Communication Power Supply Based On Interleaved PFC And LLC Resonant Full-Bridge Converter

With the rapid development of the Internet era,communication power supply as energy supply equipment is developing in the direction of high power factor,high efficiency,high dynamic response.In order to achieve the communication power supply which outputs48V/20A,and has the high quality,high dynamic response,using a two-stage converter structure to design the power supply,which included APFC circuit and the DC-DC converter.The APFC circuit is designed by interleaved Boost PFC circuit.Firstly,its control mode,working mode and working characteristics are studied.Secondly,the main circuit is designed and the circuit small signal model is analyzed based on the design objectives of this paper.Finally,a double closed-loop control system is established and verified by MATLAB simulation based on theoretical analysis.The experimental results show that the interleaved Boost PFC circuit can effectively reduce the ripple current of the total DC input current to reduce the THD,and can make the input current effectively track the input voltage to achieve high power factor.The DC-DC circuit is designed by LLC resonant full-bridge converter,Firstly,the working principle of the converter is introduced,and its equivalent model and DC gain characteristics are analyzed by fundamental wave analysis.Secondly,the working characteristics of the circuit under extreme load conditions such as no-load and short-circuit are analyzed to ensure the working stability of the converter,and the influence of quality factorand inductance ratioon the output efficiency of the resonator is analyzed to improve the working efficiency.Based on these analyses,combined with the objectives of this paper,the main circuit is designed and the small signal model is analyzed.Therefore,the integer-order PID control system is established and the MATLAB is used for simulation verification.The experimental results show that the converter can achieve primary ZVS and secondary ZCS within the full load range to get high working efficiency.However,under the integer-order PID control,the output ripple voltage of the converter is large and the dynamic response is weak,so it is difficult to be applied to the communication power supply,which has large rate of load change.In order to improve the dynamic response of the LLC resonant full-bridge converter,the fractional-order PI~λD~μcontroller is applied to the converter in this paper.Firstly,using the Particle Swarm Optimization(PSO)algorithm to tune the controller’s parameter to achieve optimal control.Secondly,using MATLAB to verify the analysis,the results show that the fractional-order PI~λD~μcontrol can effectively reduce the output ripple voltage,and the dynamic response of the converter is improved to 3-4 times that of the integer order PID control,which is suitable for communication power supply.Based on the research of communication power supply,the hardware circuit and the digital control system of the communication power supply is designed,then the related waveform and indexes of the prototype are tested.It is proved that the prototype can achieve high power factor,high working efficiency and high dynamic response,which verifies the correctness and practicability of the design.