Research On Non-Singular Terminal Sliding Mode Control Strategy Of SWISS Rectifier

With the rapid development of the power industry and the improvement of people’s living standards,electric vehicle charging piles have put forward higher and higher requirements for rectifiers.As a new step-down topology,SWISS rectifiers have natural applicability to electric vehicle charging devices.,It can be used as a medium for power transmission between the AC power grid part and the DC part of electric vehicles,and the application prospect is very broad.In this paper,the SWISS rectifier is taken as the research object,and its topology and control strategy are studied.First,introduce the research prospects and current status of SWISS rectifiers at home and abroad,analyze the principle of SWISS rectifiers,analyze the stress of various electronic devices,and analyze the modulation strategy with the smallest ripple amplitude of the SWISS rectifier inductor current.The small-signal modeling method and state-space modeling method are used to mathematically model the SWISS rectifier,so as to lay the foundation for the realization of the subsequent SWISS rectifier control strategy.Secondly,the input-side filter topology of the SWISS rectifier is improved.Using the passive damping filtering scheme,the L-CCR type filter is designed on the basis of the traditional LC type filter.Compared with the LC type filter,the L-CCR type filter will reduce the harmonics at the resonant frequency and reduce Harmonic distortion rate,and the Bode diagram is drawn through the transfer function of the filter,which proves the feasibility of the scheme;the filter trap is connected in the inductance branch of the L-CCR filter to form a filter based on the L-CCR filter Compared with the L-CCR filter,the new filter with filter trap technology can greatly increase the impedance of the branch near the switching frequency to achieve the purpose of suppressing the sub-harmonics of the switching frequency on the input side.Further reduce the harmonic distortion rate.The simulation model of SWISS rectifier topology was built by Matlab/Simulink simulation platform,and the harmonics of LC type filter,L-CCR type filter and new type filter were Fourier decomposed,and it was verified that the topology structure of SWISS rectifier based on the new type filter was in Superiority in filtering effect.Finally,the non-singular terminal sliding mode control strategy of the SWISS rectifier is improved.Using non-singular terminal sliding mode to control the SWISS rectifier,aiming at the shortcomings of non-singular terminal sliding mode in terms of response speed and ripple reduction,a saturation function is used to replace the sign function,and the sliding mode surface function is introduced into the reaching law.The adaptive variable speed exponential reaching law realizes the control of the SWISS rectifier by the improved non-singular terminal sliding mode.The non-singular terminal sliding mode control model and the improved non-singular terminal sliding mode control model of the SWISS rectifier were built on the MATLAB/Simulink simulation platform to verify the superiority of the improved non-singular terminal sliding mode control in improving response speed and reducing ripple.