| Since the 21 st century,switching power supply,as a high-efficiency and energy-saving power supply,has been developing rapidly in the direction of integration,modularization and high frequency to enhance the reliability of the power supply system.The switching power supply system has gradually replaced some traditional linear power supplies because of its advantages of small size,light weight and high efficiency.There are widely used in many fields such as new energy,computers,power electronics,communication transmission,and home appliance control.In actual production,electronic equipment has high requirements on the performance index and power quality of switching power supply,but because circuit devices are easily affected by parasitic parameters,the power supply system is easily disturbed by input voltage and load disturbance.Therefore,the switching power supply system needs to adopt an effective control strategy to obtain strong control performance and achieve good power quality.The control research of DC-DC power converter in switching power supply is relatively extensive,and its nonlinear control problem has been paid more attention by experts in the field of power electronics.In this paper,Boost DC-DC power converter as the research target,using nonlinear sliding mode variable structure control method,for the load and input voltage change range is large,can achieve strong robustness and anti-interference performance.The specific content of the paper is as follows:(1)The basic working principle of Boost converter is introduced,and its working mode in different states is analyzed.The mathematical model of the Boost converter is constructed by the state space averaging method;on this basis,the load disturbance and input voltage disturbance in the actual project are further considered,and a mathematical model that is more suitable for the reality is established.(2)The basic theory of sliding mode control is described in detail,the principle of traditional sliding mode control algorithm is expounded,and the chattering problem existing in traditional sliding mode control is analyzed.In order to improve the high frequency oscillation in the traditional sliding mode,a new sliding mode control law is introduced,and then an improved sliding mode controller is obtained.The simulation models of the traditional sliding mode and the improved sliding mode are built by Matlab/Simulink simulation software,and the simulation waveforms of the sliding mode control algorithm and the PID algorithm are compared with each other to verify the feasibility of the sliding mode control algorithm.(3)In order to suppress chattering in traditional sliding mode control,a novel second-order sliding mode control method is proposed.The method considers the state-limited problem in the actual system,and the designed second-order sliding mode controller can make the sliding variable stabilize to the equilibrium point in a finite time.The simulation results show that the designed new second-order sliding mode controller has strong robustness,good anti-interference effect,and can achieve disturbance suppression,which verifies the reliability of the new second-order sliding mode control algorithm.(4)According to the overall scheme of the designed Boost converter system,a software and hardware experimental platform is built.The hardware design mainly includes the design of the main circuit,the driving circuit and the sampling circuit;the software design includes the design of the system main program and the interrupt program.The experimental platform uses DSP TMS320F28335 as the core control,writes the control algorithm based on C language and assembly language,uses CCS7.4 software programming,and realizes the closed-loop control between the host computer,DSP and hardware circuit through the simulator.The validity of the built platform is verified by the experimental results. |
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