Development Of Torque Wrench For Power Transmission Tower Bolts

Electric torque wrench can be used in fastening power transmission tower bolts to output high torque human cannot output,raise the level of mechanization operation and reduce the work intensity of labor.There is no specific torque wrench for power transmission tower now.Ordinary electric torque wrenches are commonly heavy,with small torque and low control accuracy,and are not suitable for high-altitude operation and performance requirements of power transmission tower.For the power transmission tower bolt fastening requirements,this paper aims to develop a torque wrench for power transmission tower bolts with small volume,light weight,high intelligent level,wide application range and small torque error.According to the special needs of power transmission tower construction environment,the wrench is required to have light weight,small size and high efficiency,to be easy to carry and to extend the working time.Permanent magnet synchronous motor is used as the driving motor of power transmission tower bolt torque wrench.The bolt fastening of power transmission tower requires small torque ripple.In order to reduce the torque ripple of motor,this paper takes a special analysis on the cogging torque of permanent magnet motor.This paper analyzes the factors influencing the cogging torque and effective methods to reduce the cogging torque of permanent magnet synchronous motor.Simulation is carried out to verify the theoretical analysis.The structure of optimal rotor step skewing is then used in the driving motor design of the power transmission tower bolt torque wrench.Based on the volume limitation of the wrench and the short-term maximum load,this paper designs the permanent magnet synchronous motor by using the traditional magnetic circuit method.The main parameters of the motor are optimized by finite element analysis.Simulation results show that the motor design effectively improves the air gap magnetic field distribution and weakens the cogging torque.The overall performance of the motor meets the technical requirements.Model predictive control is used to control the torque wrench driving motor.According to the mathematical model of permanent magnet synchronous motor,simulation and hardware and software design of the controller are performed.Finally,the controller software system is tested on an existing experimental platform.Simulation and experimental results show that the model predictive control strategy has the advantages of fast dynamic response and small torque ripple.When the motor is operating under load,the bus current remains stable with small ripple,and the system performances well.