Analysis And Design Of Intrinsically Safe Flyback Converters

Electronic equipments applied in explosive conditions must meet the requirements of anti-explosive. Intrinsical safety is the optimal means for anti-explosive. Because of its light weight, small size, simple manufacture, low cost and high safety performance, intrinsically safe switching power supply will has a vast perspective.The flyback converter is a basal topology of the switching power supply, and is applied widely in practice. Therefore, analysis and design of intrincally safe characteristic of flyback converters is the vital grounds for optimial design of intrinsically safe switching power supply.The design of intrinsically safe switching power supply is mainly to design the deposited energy elements, which are inductance and output filter capacitance.The static behaviors of flyback converters are analyzed deeply. The three operating modes in the flyback converters are pointed out: CISM-CCM, IISM-CCM and DCM. The maximum output voltage and the maximum current through inductor and the maximum values of short-circuit discharged energy within the whole dynamic operating region are obtained.The intrinsically safe behaviors of flyback converters are analyzed, and the non-explosive output intrinsic safety criterion is obtained, and the explosive experiments of flyback converters are done by using the spark test equipment. Experiment results further verify the validity of the criterion.The design region of inductance and capacitance is obtained according to the requirement of output voltage ripple level and output intrinsic safety. The design region of inductance and capacitance is obtained according to the requirement of output voltage ripple level, inner intrinsic safety and output intrinsic safety within the input voltage and load ranges. The experimental results are in positive to the analysis showing the feasibility of the proposed methods.The design methods of output intrinsically safe flyback converters are proposed. The design regions of inductance and capacitance are obtained according to the requirement of output voltage ripple level and output intrinsic safety within the whole operating range.The examples are given out and the experimental results are in positive to the analysis showing the feasibility of the proposed methods.