Research On Output Intrinsically Safe Single-Stage PFC Flyback Converter

With the development of science and technology,the application of various electrical equipment in coal mines is becoming more and more extensive,such as monitoring equipment,warning equipment,control equipment,etc.,the demand for power supply is increasing.In order to ensure the safety and reliability of power supply,they must be explosion-proof,the most excellent explosion-proof performance is the intrinsically safe.With the development of coal mine technology,advanced electrical equipment has become more and more widely used in mines,the intrinsically safe power supplies have higher requirements.However,the output power of intrinsically safe supplies is still low,which severely limits its application and development.Therefore,how to improve the intrinsically safe power output power has become an urgent problem to be solved.Through the analysis of the basic theory of intrinsic safety,explosion-proof system,intrinsically safe power supply and main performance indicators,this paper focuses on the protection form and safety performance evaluation method of intrinsically safe power supply.The paper introduce several methods which can improve the output power of intrinsically safe power supply.Then it discusses the natural discharge characteristics of EC circuit model and the influence of various parameter changes on its safety performance.On this basis,the spark discharge characteristics of the cut-off EC circuit are analyzed in depth.Comparing the former two,an improved cut-off EC spark discharge circuit is studied.The model uses the operating characteristics of the MOSFET constant current region to achieve the limitation of spark current during spark discharge.Compared with the discharge characteristics of the common cut-off EC spark circuit,it is shown that the improved cut-off EC spark circuit can effectively reduce the spark discharge current and limit the spark discharge power.Combined with the improved off-type EC spark circuit discharge analysis,a high power factor output intrinsically safe switching power supply was designed to verify the accuracy of the improved cut-off protection circuit.According to the minimum ignition curve of the simple capacitor circuit in GB3836.4,the intrinsic safety nonexplosive evaluation method of the improved cut-off protection circuit is studied.Finally,the correctness of theoretical analysis and design is verified by software simulation and experiment.The accuracy of the above model is verified by experiments.