Research On Cascaded Digital Switching Power Supply Based On DSP

Switching power supply is an important part of the stable and reliable operation of modern electrical equipment.With requirements for power supply performance of electrical equipment are increasing,traditional analog control mode of switching power supply is gradually replaced by digital switching power supply.The development of DSP technology also provides strong support for advanced control theories and implementation of complex control algorithms.In view of the large volume,high voltage level and poor flexibility of experimental devices for power technology in Colleges and universities,we developed a cascaded digital switching power supply experimental platform based on TI DSP as the core controller.The experimental platform can realize wide voltage input,adjustable output,strong anti-interference and good stability,which would greatly facilitates college students to carry out related power experiments.Specifically,the main research contents of this paper are as follows:(1)The working processes of the former Flyback converter and the latter Buck converter are analyzed in detail.Based on basic working principle,the open-closed-loop small signal models of Flyback circuit and Buck circuit are established respectively.(2)Peak current control and PID control are introduced in control strategy.The control principle of variable universe fuzzy PID control algorithm is analyzed in detail.And the variable universe fuzzy control algorithm is introduced to design variable universe fuzzy PID controller to improve the dynamic performance of the system.(3)The closed-loop design of cascade converter is completed.The relationship between the closed-loop output impedance of the former Flyback converter and the closed-loop input impedance of the latter BUCK converter is analyzed.The stability criterion of impedance ratio based on the forbidden zone theory is introduced to verify the stability of the cascade converter.(4)The cascaded power system simulation model is established under the MATLAB/SIMULINK simulation environment to verify the stability of the cascaded system.And the simulation results verify the feasibility of the fuzzy-PID control algorithm and the effect of improving the dynamic performance of the system.(5)The hardware and software design of cascaded digital switching power supply is completed.According to the system performance index,TMS320F28027 ischosen as the core controller.In hardware aspect,The high-frequency transformer,main topology inductance and capacitance parameter selection,driving circuit,sampling circuit,protection circuit,protection circuit,auxiliary power supply,liquid crystal display,etc.are analyzed and designed.At the same time,the software program based on TMS320F28027 is designed with C language.Finally,an experimental prototype is built and the whole machine is debugged.The experimental results are basically consistent with the simulation results,which verifies the feasibility of this scheme.