Research On The Key Technology Of AC- DC-AC Frequency Conversion Driving For Hoist Of Auxiliary Shaft In Shunhe Mine

In mine production,hoist is the hub connecting underground and ground,whose reliability and conveying efficiency directly affect the safety and economic benefits of coal mine production.Based on the research background of the speed regulating system design of auxiliary shaft hoist in Shunhe coal mine of Yongmei group,this paper studies the key technology of high power three-level AC-DC-AC frequency conversion driving system.The lifting system adopts high power synchronous motor three-level frequency conversion speed regulation system,and the electronic control system adopts the control mode of "full-digital frequency conversion control + multi-PLC network control + upper computer diagnosis and monitoring + LAN information interconnection".To begin with,according to the design requirements of auxiliary shaft in Shunhe mine,the hoisting mode and transmission scheme of hoisting system are designed.By analyzing the kinematics and dynamics of the lifting system,the selection and verification of the synchronous motor are completed.On this basis,the main circuit of the back-to-back three-level AC-DC-AC frequency conversion speed regulation system is designed,and the selection and calculation of the main components are conducted.The working principle of three-level converter is analyzed,and a simplified three-level SVPWM algorithm based on the decomposition of reference voltage vector is introduced and verified by simulation.Aiming at the problem of midpoint potential fluctuation in three-level converter,this paper proposes a strategy of midpoint potential balance control in three-level inverter.In addition,the mathematical model of electrically excited synchronous motor is established and the vector control strategy of air gap flux oriented is studied in depth.In view of the shortcomings of the traditional flux observation model of voltage and current,this paper adopts a hybrid flux observation model,which can achieve great observation results in the full-speed range.The air gap flux oriented vector control system of synchronous motor is established,the simulation analysis of the control system is carried out,and the performance of synchronous motor speed regulation system is studied experimentally.Finally,the design of the hoisting electronic control system is carried out,including the system's high-voltage distribution cabinet,transformer,converter of synchronous motor's stator side,excitation rectifier,low-voltage distribution system and regulating cabinet,etc.The implementation scheme and protection system of the electronic control system are given.The system adopts multi-PLC network system,which is respectively used to improve the system's stroke control,fault protection,etc.,which improves the reliability of system operation.The field operation and experimental study of the auxiliary shaft hoist under different working conditions have proved the correctness of the design scheme of high-power three-level AC-DC-AC frequency conversion driving system.