The Design Of Variable Frequency Speed Regulation Of Hoist System Based On PLC And WinCC

China has a great coal reservation which stays at the front row in the world. The coal industry will still play an important role for a long time in our national economy and social development in the future. As the "artery" and "throat" of the coal mine production, the coal mine hoist will directly influence the coal production, even lead to person casualties once there is something wrong whit the hoist. So, choosing a suitable mechanical and electrical control system of the coal mine is very important and significant for guaranteeing the safety and the high efficiency of coal production. It is also very important in promoting the economy efficiency of enterprises and the sustainable development of the society.According to the survey, most coal mine hoist system in Shanxi Province still use ac induction motor to drag, regulate the speed by increasing or removing the resistance, change the motor direction of rotation by using high-voltage contactors. The Shortcomings of this control mode are:equipment operation noise, maintenance cycle is short, high energy consumption, rotor resistance takes up much room, and the regulation of speed is step. Apparently it already cannot satisfy the requirements of the coal mine production and safety production standard in the current situation.Many large-scale coal mine enterprises are seeking a kind of mechanical and electrical control system which is more efficient and energy saving in order to increasing the production efficiency and reducing the cost of mining. Regarding the above problems remaining in the traditional mine hoist, this article introduced mature technology of PLC into the mechanical and electrical control system. Using the ac inverter to regulate the speed steplessly, this increases the reliability and safety of the control system.The SIEMENS S7-300programmable controller was imported from Germany. The start and stop of the new system, security protection and safety brake was controlled by PLC; The speed feedback signal was collected by the rotary encoder installed in the motor shaft. Safety loop contains the soft safety loop and hard safety loop. The system can be brake reliably and give out sound and light alarm in case of fault.The electrical control system has two sets of PLC, one set as the master PLC, another set as the supplemented PLC. Some key signals (such as speed, container position, security protection, slowing down, over winding, and so on) are input double and multiple protections. The industrial PC is used as the upper monitor. The running state of hoist can be monitored real-timely through WinCC installed in the industrial PC. It can give an immediate alarm once there is a fault. The new system has functions such as man-machine interaction, records showing, historical memory and fault recording. Industrial PC and PLC communicate through the DP cable and all the operation and fault alarm signal can be displayed on the monitor.The electrical drive units use the inverter to regulate speed stepless. Through the PID control and parameters adjustment, the inverter can give out maximum torque in minimum frequency, receiving good low frequency characteristics, stable low speed to crawl and smooth performance of speed regulation, minimizing the electrical and mechanical impact brought by inertia, which make the system run smoothly in the whole process.The new system is easy to operate and has a very significant energy-saving effect which greatly improves the efficiency of the coal mine production.