The Research On DC/DC Converter Based On Sliding Mode Control

DC/DC converters have been widely used in traditional industrial fields such as uninterrupted power supply(UPS),DC motor drives and so on.With the enhancement of people's awareness of environmental protection,clean energies without pollution such as fuel cells,wind energy and solar photovoltaic power generation is becoming more and more popular.Since the output power and voltage of this type of clean energy are susceptible to climatic and load changes,it is very necessary to use a DC/DC converter at its output satge to provide a regulated output voltage.Nowadays,Study on DC/DC converters is mainly divided into two aspects: one is to develop a new topology to improve the conversion efficiency;the other is to design a suitable control strategy to improve stability and power quality of the system.In this paper,two kinds of sliding mode adaptive controllor(SMAC)are designed by using the double closed-loop control system based on Boost and Buck converters.They are used to realize the excellent output performance of the converter.The Boost and Buck converter are studied and analyzed respectively,and the corresponding mathematical modeling is established.The controllors are designed according to the design steps of SMC based on the mathematical model and the system stability is analyzed to demonstrate the rationality of the designed controller.Simulation comparison experiments for SMC and PID control are performed using the MATLAB.Although SMC has strong robustness,it will generate chattering in the control process,which is a disadvantage of it.Due to the chattering characteristics of SMC and the uncertainties caused by the change of system parameters and unknown external disturbances during the system working,the mathematical model is described more precisely by adding unknown bounded disturbing term.The uncertain term is adaptively approximated by a combination of SMC and other control strategy.In the Boost system,this item can be transformed to slove a set of orthogonal basis functions.By choosing a suitable adaptive law,a orthogonal polynomial approximation-based sliding mode adaptive controllor(FASMAC)has been proposed and the Laguerre polynomial is selected as the basis function of the approximation term by analyzing the results of simulation.For the Buck system,the output voltage error of the system and its derivative are taken as the input of the RBF neural network.The output of the network is used as the system approximation term,and the network weight is updated according to the adaptive law.An sliding mode adaptive controllor with the RBF network approximation(RBF-SMAC)is designed.In order to verify the performance of the SMAC for Boost and Buck converters,the simulation with Matlab and actual measurement on experimental platform for the three controllers(PIDcontrollor?SMC and SMAC)are carried out and the results show that FASMAC and RBF-SMAC have the characteristics of reducing chattering,adapting to load variation and reducing the impact of interference to the system.They can achieve excellent output performance of converter.