Browsing by Author "Achenef, Sisay"

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    Fuzzy PID Based Temperature Control of Electric Furnace for Glass Tempering Process
    (Addis Ababa University, 2017-03) Achenef, Sisay; Shiferaw, Dereje (PhD)
    Tempered glass is a safety glass processed by a controlled thermal or chemical treatment to increase its strength compared with the ordinary (or annealed) glass. In thermal tempering process, the glass is heated to a temperature just below the softening point and is then quenched rapidly in air. Thus, in thermal tempering manufacturing process temperature control of tempering furnace is the main task. Our country Ethiopia has some glass manufacturers hence we can use thermal tempering process to manufacture tempered glass. This thesis deals with the temperature control of electric furnace. The temperature of electric furnace is controlled to a desired value. In tempered glass furnace industry, the widely used controller for temperature control is conventional PI and PID controllers. Since electric furnaces are nonlinear and time varying processes, using PID controllers is difficult to meet the control requirement. Because they are not robust, haven’t good dynamic response and have large overshoot. Hence in this thesis, fuzzy logic controller which is fault tolerant and nonlinear controller is used to improve the PID and achieve steady state and transient requirements. Therefore, in this thesis a model of glass tempering furnace is prepared using MATLAB/SIMULINK and then fuzzy PID controller has been designed and simulated and its performance has been compared with conventional PID controllers. The performance of the controllers is compared in terms of disturbance rejection, transient and steady sate performance. It is observed from the simulation results that the average overshoot is 2.129%, rising time is 44 seconds and the settling time is 170s seconds with the proposed fuzzy PID controller while overshoot is 16.129%, rise time is 45 second and settling time is 290 seconds with PID controller. Moreover, the robustness and disturbance rejection of the controllers is checked by parameter variation like time constant, delay time & DC gain and giving disturbance signal after settling time respectively. It is further observed that the proposed controller has better disturbance rejection and more robust. Key words: Glass tempering furnace temperature control, Fuzzy PID controller, PID controller.