Research On Main Drive Speed Control System Of Rolling Mill

With the rapid development of market economy,a variety of industries,including automobile,radio,instrument electronics,aerospace and many other fields,have asked a great deal to strip steel,especially the specifications,varieties,quality and performance.Cold rolling is a great important part of the moderm strip steel production,the improvement of its technology makes important meaning.The main drive system of tandem cold mill is the key component of strip steel production and it requires that the speed control system must have excellent overloading ability,great static and dynamic performance,as well as quick response.What's more,the disturbance-resistant ability needs to be robust.The background of this research is the Benxi steel third cold rolling mill.Firstly,make analysis of the system by studying on the main drive speed control system of tandem cold rolling mill,mainly on rolling process,main equipment,control structure,speed regulation circuit,characteristic of speed control system and the elements which affect the system performance.Based on the coordinate transformation,rotor flux orientation strategy is adopted to get the vector control model.Secondly,designing the rotor flux observer by the improved VM and IM model.The system adopts direct vector control strategy to confirm the system structure which has three closed loops including speed loop,current loop and magnetic chain loop.Finally,PID controller is designed.The excellent property of the cold rolling mill main drive vector control system relies on the parameter of electric machine.When system is running,the parameter of electric machine such as rotor time constant and rotational inertia is variational.Last but not least,the load of mill is non-linear and uncertainly.All these changes will affect the system performance.Aimed at these problems,linear active disturbance rejection controller is introduced.By using linear extended state observer to observe the disturbance factor and make compensation,the main drive of cold rolling mill based on LADRC and vector control is designed.Simulation results indicate that the new system has obvious inhibition to load disturbance,meanwhile the system has strong robustness to parameter perturbation.