A Study Of Variable Structure Fuzzy Temperature Control System To Resistance Furnace

Resistance furnace is a typical dynamic model of uncertain control objects, whose characteristics are nonlinear of model parameters, time-varying, unipolarity of the process of temperature rising, large thermal inertia, and lagging capacity and so on.Especially, when the properties of the model change is very serious,such as the state of working temperature and load working conditions change,it needs to change the controller parameters or algorithm to obtain good temperature control index.The paper analyzes the characteristics of resistance furnace in different conditions and the in different operating conditions, expounds the influence of the different algorithms of temperature control index, puts forward scheme of the resistance furnace fuzzy integral variable structure control, designs the fuzzy variable structure controller, and overcomes the shortcomings caused by operating conditions and load state change of temperature controlling index dropped, At the same time,it has good robustness.Two different fuzzy controller are designed according to the different characteristics of the work state of temperature and load resistance furnace,and they respectively work in a different error range, when the actual temperature is close to the terminal control,integrator eliminate residual and improve accuracy of temperature control.That output of fuzzy control and output of integral time accumulate are as output value of time proportional controller, controls the power of the resistance furnace and controls temperature.The paper introduces design methods of the fuzzy controller, the time integral variable structure controller, time controller.And has carried on the MATLAB and Simulink model simulation, determined the feasibility of the control system scheme, and adopted Siemens S7-200 PLC program design to realize the resistance furnace temperature fuzzy integral variable structure control system. Through the MCGS configuration software, built a PC interface monitoring system. Through making a lot of applied research and continuous optimization design and experiment, good dynamic and static temperature control index are obtained.