| Winding tension control has been widely used in fields of paper making, spinning, avigation and space flight, and other industries. In manufacture of winding prestressed dies, spread of tension of outer steel layers has an influence directely on the life and strength of dies. So it is a crucial element to improve the precision of prestress of steel layers of dies in the process of tension control. Compared with steel strip winding prestressed dies, the present steel wire winding prestressed containers have character of high cost, long producing cycle and comparative low order, for which it can't be applied to super inner-stress environment, in which it may be destroyed and failed due to minor prestress provided by it. So it has importantly practical and creative values to study winding tension control applied in the field of manufacture of steel strip winding prestressed dies,which can be applied to the super inner-stress working environments. For a stable running control system for steel strip winding tension control, the primary control target requires that the actual winding tension follows the expected winding tension in order to get an expected prestress in the steel strip winding around the core. The next target is to make the steady conveying velocity trace our expected velocity. The controlled plant of steel winding tension control system is of complex of multi-variables, intensive coupling and nonlinearity, which is difficult to deal with in conventional way using in linear systems. So how to obtain a satisfying steel strip winding tension and a steady steel strip conveying velocity is a problem to be solved.Fuzzy control, as an important branch of intelligent control theory, which has been developing maturely in theory and technology, has been applied widely to the solution to the control problems of nonlineartity, strong coupling and large delay system. So, on the base of analysis of steel strip winding tension control, this subject is supported by the natural science foundation—study of design of varying tension of steel strip prestressed dies in theory and experiment ( NO. 50875111), has proposed a control scheme of adoption of double motors modes. On the simulation platform of MATLAB/SIMULINK, them main parts of drivers of unsychronious motor and servo motor--- vector variable frequency and Current Lagging-loop PWM Inverter has been analysed and design in detail. The control system modes of winding tension on the basis of double motors have been built through mechanics analysis. Different ways for winding tension control has been analysed and compared and different algorithms has been discussed in detail to decide a proper scheme for steel stape winding tension control system. And feedback way of velocity regulation tension control has been selected to realize tension control and the modes of double feedback loops of currency and velocity for sevo motor control has been fixed to gain our expected conveying velocity. In order to improve the whole performance of control, the idea of Fuzzy-PI double modes control has been proposed to improve the transient performance and steady performance of the process of tension control and velocity control. Various methods of multimode control are adopted more and more widely to improve the performance of control systems. The problem of smooth switching of different controllers is the key in application of multimode control. Aiming at the problem during switching between Fuzzy control and PI conrol, after analysis and discussion of different switching methods, the idea of switching at natural switch point has been proposed. The feasibility of idea of switching at natural switching point is discussed. And then Fuzzy-PI double modes smooth switch at natural point has been designed in detail to decrease influence brought by the difference between outputs of different controllers at the moment of switch. In tension control system for winding machine, motor sometime works under minus load circumstance, in which electromagnetic torque acts as drive, but its direction is opposite with the rotary direction of motor because of load torque. In order to solve the problem of velocity oscillation during steady process under the minus load circumstance. The minus load circumstance of motor running is analyzed in detail, and a minus load model of steel winding tension control system for rewinding system is built to mode the real rewinding process. A novel thought of introducing Fuzzy control into steady process to improve steady performance has been proposed and designed in detail to reduce the band of error. Finally the idea of decoupling control between tension and velocity has been proposed, analysed and designed to further improve transient and steady performances of tension control system. In the respect of practice, the equipments of winding control and rewinding control have been debugged respectively. And the precision of the whole winding tension control system has been evalued to provide a feasibility proof.On the base of analysis and design, simulation built on the platform of MATLAB has been done to prove these novel ideas and thoughts,which has been proposed previously. The simulation results show that Fuzzy-PI double modes switching control can bring better effect on development of tension performance and velocity performance—not only transient developed by Fuzzy control but also steady performance improved by PI control, realizing smooth switch, which means that the big impulse of electromagnetic torque has been avoided. And the result can offer effective reference for other multimode control design. The range of oscillation in steady performance has been reduced by one order after Fuzzy control has been introduced into steady process, which is designed on the base of Fuzzy-PI double modes soomth switching control, though some drawbacks has been brought due to the very high switch frequency. Feedforward decoupling control can lower the intensity of couple between winding tension and conveying velocity due to the winding tension caused by difference of velocities between rewinding velocity and winding velocity, as can further improve the precise of tension and velocity control. Study of this subject and related result of this stdudy has good practical significance and reference value, which can provide a reference to practice, although further study is required to solve problems im practice. |
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