Sliding Mode Control Research For Cement Combined Grinding System Based On Typical Working Condition

Combined grinding system is an important part of the cement production. Because of its characteristics of nonlinear and big lag, combined grinding systemhas always been the difficulty in the cement production control.Due to the strong robustness for perturbation of system and external disturbance in the sliding mode,sliding mode controlhas been widely researched and engineering application.Therefore, this paper studies sliding mode control method and application of combined grinding system,which is based on the typical working conditions.the main research of this paper is as follows.(1) Combining the combined grinding system, referring the technology, the mathematical model of mill load is established.Learning from the experience operators, we obtain the main factors of affecting combined grinding system stability and efficiencyarewarehouse material level and the mill load. Select scattered classifier speed and feed quantity to control the mill load and warehouse material levelrespectively. Combining the history data, the mathematical model of mill load is establishedutilizing the least square method. The simulation results show that the established model can fit the changing process of the mill current.(2) According to the mill load model which is established in(1), the nominal mill load sliding mode controller is designed. To ensure any point in the system can reach the sliding surface in finite time and make the approaching movement have better dynamic performance.The designed controller uses exponential reaching law.In order to reduce the chattering of the system and increasethe approach speed, the reaching law is designed as the adaptive exponential reaching law. And the accessibility and stability of the sliding mode surface are proved. The simulation results prove that thedesigned controller can realize the tracking tasks of the mill load.(3) Because the actual combined grinding system exists the internal parameters perturbation and external disturbance, the designed method of the disturbed mill load sliding mode controller which is based on disturbance observer is proposed. In order to estimate the mill load disturbance of disturbed system, the disturbance observer is designed and its convergence is proved. Combining sliding mode controller of(2), controller structure of disturbed system is given and the stability of closed-loop system is proved.The simulation results prove that the designed controller can realize the tracking tasks of the mill load.(4) In order to facilitate engineering application, combining with Bang-Bang control, the automatic control software of combined grinding system is realized. From the perspective of control and software realization, the control scheme and the software implementation scheme of combined grinding system is proposed, the concrete realization ofcombined grindingautomatic controlsoftware is given.