Basic Research On Application Of Magnetically Integrated Intrinsically Safe Switching Converter

Electronic equipment used in petroleum,chemical,coal mine and other flammable and explosive hazardous environments must meet explosion-proof requirements.Intrinsically safe electrical equipment needs to limit the energy in the circuit when designing.Through parameter selection and control circuit design,the potential spark energy in the circuit is limited to the minimum ignition energy,the surface heating temperature of electronic components and wires is limited to the limit temperature.Therefore,studying the discharge theory of intrinsically safe circuits can provide theoretical support for the design of intrinsically safe circuits,and provide technical support for the design of intrinsically safe electrical products,especially for the design of intrinsically safe switching converters.It can also shorten the development,design,and development cycle of intrinsically safe products,reduce costs,and have positive practical significance.The mathematical model and circuit analysis method were used to study the intrinsically safe circuit discharge model.Based on the analysis of the existing intrinsically safe circuit discharge model,the simple intrinsically safe circuit model was improved and the inductor-capacitor combination intrinsically safe circuit model was established and provide theoretical analysis basis for designing,testing,and evaluating the performance of intrinsically safe circuits.On this basis,the output intrinsically safe forward converter is studied.In order to improve the intrinsic safety performance,at the same time reduce the volume of the forward converter,increase the power density,reduce the output current ripple,the filter inductance of the forward converter magnetically integrated with the forward transformer.The modal analysis of the CCM and DCM operating modes of the magnetically integrated forward converter was performed,and the voltage gain expressions of the magnetically integrated forward converter in the CCM and DCM operating modes were obtained;Based on the analysis of the coupled inductor,the terminal voltage conditions of the filter inductor of the forward converter and the magnetic integration of the transformer are given,and the design range of the winding turns ratio and the coupling degree of the magnetic integrated forward converter is obtained by graphical methods;The characteristic curve is used to describe the expression of the filter inductor current of the forward converter,and the optimal coupling value range for reducing the inductor current ripple is obtained.By equivalent treatment of the expression of the inductor current,the equivalent inductances of the forward operating modes of the forward converter are obtained.According to the critical conditions of the CCM and DCM operating modes,the critical inductance of the forward converter is obtained by using the equivalent inductance,provides a basis for the study of the converter’s output ripple voltage analysis to divide the converter’s intrinsically safe inductor design area.According to the design area division,the maximum output voltage ripple of the converter under CCM and DCM operating modes was analyzed using the regional critical inductance,and the optimal range of the converter’s intrinsically safe inductance design was obtained.By analyzing the output short-circuit release energy of CCM and DCM in the whole working range of the converter,the relationship between the maximum output short-circuit release energy and the filter capacitance,inductance,coupling degree,turn ratio of the secondary winding to the inductive winding is obtained,and the design range of optimum coupling degree of integrated magnet for intrinsically safe magnetic integrated forward converter is given.By designing the integrated magnetic parts of the magnetic integrated forward converter,the magnetic circuit-circuit dual conversion method is used to derive the equivalent-circuit model of the magnetic integrated magnetic-parts.The circuit simulation of the magnetically integrated forward converter is performed using the equivalent circuit model.The simulation results verify the correctness of the design theory.An experimental prototype was designed,and the experimental waveforms obtained from the experimental tests were analyzed.The results verified the correctness of the theoretical and simulation analysis of the output intrinsically safe integrated forward converter.The improved discharge model of intrinsically safe circuit presented in this paper plays an important role in the design of intrinsically safe electrical systems,and the design theory of the output intrinsically safe magnetic integrated forward converter presented in this paper is guidance and can be used for reference in the design of intrinsically safe switching converters.There dissertation 89 figures,11 tables and 167 references.