| High nitrogen steel is not only superior in mechanical properties,but resistance,which is widely used in military industry,aerospace and other fields.In actual production,the high nitrogen steel prepared by ordinary electroslag furnace has the problems of low nitrogen content and low material yield.The pressurized electroslag remelting is an effective process method to solve these problems and realize the requirements of nitrogen addition and pure steel purification at the same time.This process is not only a new process in the field of electroslag metallurgy,but also an indispensable process technology for the production of high nitrogen steel at present.The water-gas balance control device and its control technology are the necessary technology to realize the high-pressure nitrogen control in the smelting room,and also one of the key core technologies to ensure the completion of the production of pressurized electroslag remelting.In this thesis,the water-gas balance control device and control method of pressurized electroslag remelting are taken as the research object and the main research contents as follows:(1)Firstly,the equipment composition and control requirements of pressurized electroslag remelting water-gas balance system are analyzed in detail to ensure that the design of the control system can be completed.At the same time,the control methods of pressure and water pressure are discussed respectively.Then,combined with the actual pressure setting requirements of pressurized electroslag remelting process,to ensure the balance of water pressure and air pressure as the control goal,the water and gas balance control system in pressurized electroslag remelting is modeled and the nonlinear control system model is obtained.The Backstepping(adaptive backstepping)algorithm was used to design the controller and determine the control method.Finally,according to the established mathematical model and the confirmed control method,Simulink simulation experiment platform was built to verify and optimize the controller algorithm.(2)In the water-air balance system,there are many problems that cannot be ignored,such as input dead zone and full state constraint,which have a great impact on the system performance and may even lead to system instability.In order to overcome the above problems,an adaptive neural network control method is proposed for this class of uncertain nonlinear systems.Firstly,the obstacle type Lyapunov function is introduced into the backstepping controller frame,and the radial basis function neural network is used to approximate the unknown nonlinear function.Meanwhile,the adaptive adjustment mechanism is designed to dynamically compensate the input dead zone and ensure that all the system states do not violate the predefined constraint interval.In the expected time,all signals of the closed loop system are guaranteed to be bounded and tracking errors converge to a bounded compact set.Finally,the simulation results demonstrate the effectiveness of the proposed control method. |
