Research On The Control System Of External Rotor Permanent Magnet Elevator

In the coal mine production system,the mine hoist is used to connect the underground and the ground,the safety and efficiency of its work plays a key role in the safety and efficiency of the coal mine production.The research object of this paper is the control system of permanent magnet outer rotor hoist,aiming at the problem of poor low-frequency starting ability of permanent magnet outer rotor hoist,starting failure or starting slip;And the vector control system and the direct torque control system have the problem of large torque ripple.The above problems are studied and solved from the aspects of operation characteristic research,control theory research and simulation analysis,simulation test system design,industrial test and so on.In this paper,the operating characteristics of mine hoisting system are studied,kinematics analysis is carried out,based on the velocity diagram of five stages and the impact limitation theory,it is pointed out that the trapezoidal acceleration curve can reduce the impact of starting and smooth starting..Then,it focuses on the study of the start-stop control process of mine hoist,summarizes the commonly used start-stop control methods and points out the shortcomings of each method.On this basis,it proposes the anti-impact starting control method and the multiloop constant deceleration braking control method of the permanent magnet outer rotor hoist control system.Finally,the starting characteristics,efficiency,energy saving and stopping control of the permanent magnet outer rotor hoist are compared with the traditional mine hoist,and the characteristics and existing problems of the control system of the permanent magnet outer rotor hoist are pointed out.Aiming at the problems existing in the control system of permanent magnet outer rotor hoist,the low-frequency starting characteristics of the permanent magnet outer rotor hoist are studied,and the problem of poor open-loop starting characteristics is pointed out.A highprecision encoder and software subdivision algorithm are used to detect the outer rotor position to form a closed-loop control system.Based on the vector control theory,the vector control system model of the permanent magnet outer rotor hoist is designed and simulated.For the problem of large torque ripple,based on the sliding mode control theory,a sliding mode speed controller is designed to replace the PI controller,and the sliding mode control algorithm is applied to improve the vector control system of the permanent magnet outer rotor hoist,which reduces the torque ripple and enhances the load anti-disturbance ability and robustness.Based on the theory of direct torque control,a model of the direct torque control system of a permanent magnet outer rotor hoist is designed and simulated.For the problem of large torque ripple,based on the second-order Super-twisting sliding mode control algorithm,a sliding mode flux and torque controller is designed to replace the traditional Bang-Bang controller,and the traditional direct torque control system is improved and optimized.The simulation results show that the speed overshoot is obviously suppressed,the torque ripple is obviously reduced,and the torque response speed is faster.Based on the design specification of multi-rope friction hoist,this paper designs a set of double-rope friction permanent magnet outer rotor hoist simulation test system,including the design and selection of hoist,wire rope,gasket,etc.,wire rope anti-skid check,and main mechanical components The design,mechanical analysis of key components to verify the rationality of the design,complete the selection of control system equipment,the drawing of electronic control schematic diagrams and the elaboration of the operation control process.The no-load starting characteristic test of a prototype of permanent magnet outer rotor hoist is completed,which shows that the voltage curve,the current curve and the electromagnetic torque have certain pulsation.The no-load starting characteristic test of permanent magnet synchronous motor is completed,which shows that the voltage curve,the current curve and the electromagnetic torque all have certain pulsation,indicates the need for accurate control of a closed loop control system..The velocity curve,current curve and oil pressure curve of the control system of permanent magnet outer rotor hoist based on vector control strategy were measured.The results show that the starting stage is in line with the characteristics of ultra-low frequency stable starting,and the starting current is small and the starting impact is small.The current value and electromagnetic torque of the accelerated and constant speed operation segments fluctuate significantly,which is consistent with the simulation results of the vector control system of the permanent magnet outer rotor hoist in Chapter 3.The experiments of normal braking process under no-load lowering and lifting conditions are completed.The results show that the speed and torque(proportional to the current)of braking process have great pulsation,which is consistent with the simulation results of traditional vector control system in Chapter 3.Therefore,it is necessary to add sliding mode control and other algorithms to the existing vector control system for further improvement and optimization in order to weaken or eliminate the speed and torque ripple.