Development Of High Power Intrinsically Safe Power Supply For Mining

The mine intrinsically safe power supply is used as the power supply equipment for various control,monitoring,communication and alarm electrical equipment in the coal mine.Its stable,reliable and safe power supply is very important for the electrical equipment in the coal mine.However,with the continuous advancement of coal mine science and technology,the power of mine intrinsically safe power supplies is becoming more and more difficult to meet the growing demand for power supply for underground intelligent,integrated,and informationized electrical equipment.Security presents new challenges.Therefore,the development of a set of intrinsically safe power supplies with excellent intrinsic safety characteristics,large output power,and a wide range of use is of great significance to the safe production of coal mines and the safe and stable work of coal mine electrical equipment.Through investigation and research on the existing domestic and foreign mine intrinsically safe power supplies,it is found that the current mine intrinsically safe power supplies are generally less than 20 W.At the same time,there are problems such as slow circuit dynamic response,reliability and safety cannot be guaranteed.Aiming at the above problems,this paper takes the mine intrinsically safe power supply as the research objective,and conducts in-depth research on the overall design scheme,equivalent circuit model,intrinsically safe protection mechanism,hardware circuit design of the intrinsically safe power supply,etc.The specific research content is as follows:The overall design plan of intrinsically safe power supply was formulated.Introduced in detail the structural characteristics,current limiting methods,protection modes,common topology circuit structure and technical requirements of the intrinsically safe power supply,compared the differences and advantages and disadvantages,and determined that the intrinsically safe power supply of this design adopts high-frequency transformer Safe power supply structure,cut-off current limiting mode,back-end protection mode,select flyback topology circuit structure for design.The short-circuit spark discharge characteristics of the electric potential capacitor circuit and its influencing factors are studied.First,analyze the intrinsically safe power circuit model,which is equivalent to a capacitive circuit,and analyze the discharge process;on this basis,it is equivalent to a potential capacitor circuit,an equivalent mathematical model is established,and the equivalent spark discharge current and spark are obtained by solving the mathematical model.Mathematical expressions of discharge voltage,spark discharge power and spark discharge energy;according to the actual design of this subject,simulation parameters need to be set for numerical simulation,and the influencing factors of spark discharge and short-circuit spark discharge characteristics are analyzed.It is the hardware circuit of the subsequent high-power intrinsically safe power supply The design and parameter setting lay the theoretical foundation.The short-circuit spark discharge characteristics of the electric potential capacitor circuit and its influencing factors are studied.First,analyze the intrinsically safe power circuit model,which is equivalent to a capacitive circuit,and analyze the discharge process;on this basis,it is equivalent to a potential capacitor circuit,and the equivalent spark discharge current,voltage,power,and power can be obtained through analysis and calculation of the mathematical model.Mathematical expression of energy;according to the actual design of this subject,simulation parameters need to be set for numerical simulation,and the influencing factors of spark discharge and short-circuit spark discharge characteristics are analyzed,which lays a theoretical foundation for the subsequent high-power intrinsically safe power supply hardware circuit design and parameter setting.The intrinsically safe power supply hardware circuit is designed.Combining the research objectives of the subject and the analysis of the spark discharge characteristics of the equivalent circuit of the intrinsically safe power supply,determine the block diagram of the intrinsically safe power supply in this design and the functions of each module,formulate functional indicators and technical indicators;design the main circuit of the intrinsically safe power supply,which is divided into rectifier and filter input Circuit,high-frequency flyback circuit and rectifier filter output circuit are three parts;the key components of the main circuit including rectifier bridge,high-frequency transformer,main circuit MOS tube and output rectifier diode are selected and parameterized;the control chip UC3842 is introduced The basic working principle,the control circuit is designed according to the basic working principle of UC3842,and the feedback circuit is designed with the optocoupler and the three-terminal adjustable shunt reference source TL431 as the core;the intrinsically safe protection circuit based on the fault current change rate is designed,which is divided into The four parts of the overvoltage detection circuit,the fault current change rate detection circuit,the self-recovery circuit and the soft start circuit lay the foundation for the subsequent hardware debugging and experiment of the intrinsically safe power supply.The Pspice simulation software was used to simulate each part of the intrinsically safe power supply circuit in this design,and a simulation simulation circuit model was built to verify the intrinsically safe power supply startup condition,over-current and over-voltage protection,short-circuit protection and self-recovery functions;built the intrinsically safe power supply The experimental test platform has performed performance tests on the conventional performance of intrinsically safe power supply,over-current protection circuit,over-voltage protection circuit,short-circuit protection circuit,self-recovery circuit and soft-start circuit.Simulation and experimental test results show that the hardware circuit of the intrinsically safe power supply in this design is reasonable,and the output power can reach 30 W,which can meet the needs of underground electrical equipment.