Disturbance Influence And Performance Improvement Of Sliding Mode Controlled Boost Converter

As a widely used power converter,the output voltage quality of DC-DC Boost converter has always been a key problem restricting its application.As far as the circuit itself is concerned,Boost converter belongs to a typical class of nonlinear time-varying system and is affected by disturbance factors such as circuit parasitic parameters.From the point of view of controller design,although Sliding mode control(SMC)due to its robust performance has been widely used,the inherent chattering problem of SMC can induce serious harmonics,which seriously restricts its performance.Improvement of performance.This paper will study the factors affecting the output voltage quality of Boost converter from two aspects of circuit modeling and control,which will be of great reference value for improving the performance of Boost converter in essence and in an all-round way.The influence of parasitic parameters of Boost converter circuit on its high and low frequency performance is studied.Considering the existence of parasitic parameters from the power switch,capacitor and inductance energy storage components,diode forward voltage drop and resistance,the equivalent conversion of the Boost converter model is established under the continuous conduction mode of inductance current,and its transfer function model is deduced.The mathematical influence of different parasitic parameters on the high frequency and low frequency performance of the circuit is analyzed,which is verified by simulation and experiment.Considering the unmodeled dynamics of sensors which are often neglected in the process of modeling,the transient performance of sliding mode controlled Boost converter with stable output of sensors is studied.Considering the static and dynamic characteristics of the sensor,a singular perturbation model of the sensor is established by choosing its rising time as the perturbation factor.The constraints to ensure its stable output are given,and the existence of harmonics in the system is proved within the time scale of singular perturbation theory.The mathematical relationship of harmonic sub-frequency characteristics of Boost converter output voltage is quantitatively given by the describing function method.Finally,taking linear Hall sensor ACS712 as an example,it is proved that the unmodeled dynamic effect of sensor cannot be ignored.Aiming at the harmonic problem of sliding mode controlled Boost converter,a harmonic suppression method based on multi-phase sliding mode is studied.The multi-phase sliding mode controller of Boost converter is studied and designed to generate harmonic canceling in the sum of the inductor currents.The harmonic suppression is analyzed for the two-phase sliding mode and simulations are done for the two-phase and four-phase sliding mode under steady state.Aiming at the state observation of sliding mode control Boost converter,the design of sliding mode controller in current control mode based on sliding mode observer is studied.An auxiliary sliding mode observer is designed.By observing the output voltage of Boost converter and calculating the current of circuit on-off control,the sliding mode observer is directly used in the design of sliding mode controller instead of the sensor in traditional circuit.Finally,the simulation and experiment based on d SPACE 1401 is carried out to validate the designed observer.