Research On The Control Strategy Of The Main Shaft Of NC Machine Tools

With the development of advanced manufacturing technology,the equipment manufacturing industry has made tremendous progress,as the workhorses of the manufacturing industry,CNC machine tools to be a key role.Tiny precision differences and reliability of the number control machine tool have been a worthy research topic.In this paper,the speed control strategy is studied based on the technology of direct torque control for the spindle motor of CNC machine tools.The specific research contents are as follows:Combining work principles and mechanical structure of CNC machine tools,clearly on the objective and target of control system and establishing the mathematical model of the three-phase asynchronous motor are based on direct torque control technology,and the design of NC machine tool spindle motor control system.The observation of asynchronous motor stator flux,electromagnetic torque of asynchronous motor is done according to the input speed control,in order to achieve aim of speed.Because the stator flux observation is the key link of direct torque control,its performance will affect its precision and stability of the system control,in order to improve the performance of the stator flux observer,the stator flux observer model based on the low flux filter,and compared with conventional stator flux observer model,thus verify the superiority of the former.In order to solve the traditional direct torque control torque ripple problem,based on the sliding mode variable structure control theory,integration of the space vector pulse width modulation(SVPWM),designing sliding mode variable structure controller and its application to the asynchronous motor direct torque control system,and carries on the analysis and comparison with the traditional direct torque control system.The former can reduce the torque ripple,the CNC machine run more smoothly and quickly,enhance the quality of the work of the CNC machine tools.By taking advantage of numerical simulation software of MATLAB Simulink simulation module of asynchronous motor and direct torque control system simulation model.It turned out that,design of synovial variable structure direct torque control system has some advantages include high response speed,high stability,high accuracy.By comparing traditional asynchronous motor direct torque control system,that has made great progress.