Fuzzy Logic Control Strategy for a Three-Phase Electric Arc Furnace

The electric arc furnace is a nonlinear load, this nonlinearity being given by the electric arc. In this paper is performed a study in order to control the current of a three phase electric arc furnace. The control strategy is carried out in Matlab/Simulink and is used a model of the electric arc that was developed by the authors of this paper. The type of the controller used in this paper is a fuzzy logic one. This fuzzy system has the error and the change of error as inputs and the sending command to the execution element as output. The system is tested in two ways. The first case is when is modified the value of the reference parameter. In order to follow this reference parameter the controller should send command to the execution element so the length of the arc will be modified and be obtained the value of the set point parameter. The second case is when injecting disturbances at the length of the arc and the controller should reject these disturbances so the reference current is obtained again. The response of this system, tested in a closed-loop, illustrates that this proposed system has good dynamics, small overshot, good answering time, follow precisely the value of the reference parameter and reject well injected disturbances.