Mine Explosion-proof And Intrinsically Safe Variable Frequency Variable Speed Device

In the process of coal mine production,the use of belt conveyor in transport link can significantly improve the production efficiency of coal mine enterprises.The belt conveyor drive type mainly has the hydraulic coupling,the magnetic coupler,the variable voltage control,the variable frequency control several ways,hydraulic coupler volume is large,the magnetic coupling technology is not mature,variable voltage control is not suitable for heavy load starting,variable frequency control has the characteristics of flexible control,convenient operation,high performance,widely used in coal mine belt conveyor drive system.The characteristics of coal mine has high gas,high dust,general inverter usually cooled by air convection,not suitable for work in the coal mine environment,if the general inverter in the explosion-proof shell,then the power devices in the explosion-proof shell heat will have problems;all control terminals outside the explosion-proof shell must have the characteristics of intrinsically safe;the belt conveyor is constant torque load,requires a high starting torque,acceleration is not too large,to prevent slipping of coal.According to the characteristics of coal mine production and the special working environment of belt conveyor,designed a kind of mine explosionproof and intrinsically safe variable frequency variable speed device.The main research work and innovative points of this paper are as follows:Firstly,a constant torque control device for belt conveyor is developed,several ways to realize the sealing of the joint surface of explosion-proof shell,when a fault occurs in the explosion-proof shell,effectively play the role of explosion.a circulating water cooling system is designed,which can meet the requirement of heat dissipation in the long run of rated load.Secondly,electrical main circuit design and component selection,including programmable logic controller(PLC),power,filter,brake and other circuit design.The position optimization of various components,the use of magnetic ring,shield,filter,the actual EMC test results meet GB12668.3-2003(adjustable speed electrical power drive systems-Part 3: EMC product standard including specific test methods).The intrinsically safe type electrical components,ensure the safe operation of the device in special environment.Thirdly,control system hardware circuit design,including control circuit,interface circuit,switching power supply circuit and drive circuit.Optocoupler,over-voltage and over-current protection,temperature protection,phase loss protection,grounding protection,drive protection circuit and so on,to ensure the reliable operation of variable frequency device.Finally,the software control program of frequency control device is worked out,the SVPWM modulation algorithm is adopted,and the programming technique of SVPWM modulation algorithm is presented.Software watchdog,PWM dead time,function in the RAM running,practice proves that the control system can ensure the reliability and real-time.