Analysis And Design Of Intrinsically Safe Buck-Boost Converter On Considering Filter Capacitor With ESR

With the increasing penetration of automation in coal mines,petrochemical and other energy enterprises,intrinsically safe power supply is more and more widely used in monitoring,communication,instrumentation and automatic control systems in these flammable and explosive environments.Buck-Boost converters have the advantages of small size,high efficiency,and light weight,so they have broad application prospects in hazardous environments such as coal mines and petrochemicals that are flammable and explosive.At the same time,users have put forward new requirements for the output ripple voltage accuracy,volume and efficiency of the intrinsically safe power supply and other performance indicators,and The design of filter capacitor is closely related to these performance indexes.Too much capacitance will affect the intrinsic safety performance of the power supply,and too small will cause the output ripple voltage to fail to meet the electrical performance requirements.However,the intrinsic safety switching converter should not only meet the intrinsic safety performance index,but also meet the electrical performance index.Therefore,selecting appropriate parameters has an important impact on the overall performance of the power supply.The traditional design method of intrinsically safe power supply adopts the ideal model of the converter,but the Buck-Boost converter is affected by its own parasitic parameters in actual operation,the intrinsic safety performance and electrical performance will have some errors with the ideal model.Because the mathematical model of the output ripple voltage of the converter is closely related to the selection of the capacitance and inductance,and the selection of the capacitance and inductance will seriously affect the output short-circuit discharge energy of the converter,so it is particularly important to study a more accurate mathematical model of the output ripple voltage for the design of intrinsically safe power supply.In order to solve the problem that the traditional analysis method of output ripple voltage is not accurate enough,the ripple voltage modeling method of Buck-Boost converter considering the equivalent series resistance of filter capacitor is proposed.The study found that there are five types of output ripple voltage waveforms in CCM and DCM,and theanalytical expressions of each type of output ripple voltage in different modes were derived.Finally,the correctness of the analysis of the distortion mechanism of the output ripple voltage was verified by experiments.At the same time,it shows that the mathematical model of ripple voltage has high precision.In order to further promote the application and development of intrinsically safe Buck-Boost converter in energy enterprises,the influence of ESR on intrinsic safety performance of Buck-Boost converter was studied.The relationship between the peak inductance current and the output ripple voltage of the converter was summarized.The maximum peak inductance current and the maximum output ripple voltage in the dynamic range of the converter were discussed.On this basis,an optimal design method for the parameters of intrinsically safe Buck-Boost converter in the dynamic range of input voltage,load resistance and ESR maximum was proposed,and compared with the traditional design method.The experimental results show that this method can effectively reduce the margin of output filter capacitance selection and improve the intrinsic safety of Buck-Boost converter.