The Design Of Mould Level Controller

The control system of mould level is crucial to improve the slab quality in the continuous casting process. PID controller is used in the traditional mould level control and it has some defaults, such as: at the start-up or finishing period of casting or during the changeover of tundish overshoot is high and adjusted time is long, stopper and the submersed nozzles lead to the accuracy of control become bad; the abrupt falloff of block in the submersed nozzles makes the level acutely fluctuation, and PID control can not overcome the disturbances resulted from the change of casting speed.Based on the careful analysis on the difficulties, which the mould level control system encounters, and scrupulous research on many controllers which applied to the mould level control system, a controller which used structure singular value μ method is adopted in this paper, which aimed at taking place of the old PID parameters controller for which bad control effect. Although the structure singular value μ method has been applied in many fields, it is not reported that the structure singular value μ method be applied to the mould level control system, according to the present information.When we design the controller using the structure singular value μ method, because it is very difficult to design μ controller directly, it usually uses D-K iteration proceeding, which uses D and K carried through minimization step by step. That fixed up D first, using H_∞ theory find out the problem of the minimization of K, getting the optimal solution. Then fixed up K, using convex optimization theory, find out the optimum nominal matrix D. μ synthesis can be solved through iteration. Base on the number of iteration the controller that satisfied precision limited could be found.After researched structure singular value μ method, simulation experiments are shown in this paper, which demonstrated this controller is feasible. The result of the experiment manifests: the controller using structure singular value μ method has the following character: short transient time; excellent control accuracy and so on.