Control of an Induction Motor Using the Relay Method Approach

Abstract

The authors approach by means of this paper an induction motor control for the rotation of a furnace hearth. The rotation regime of the rotary hearth furnace, used for heating up billets in order to prepare them for the rolling process, is jerky with stops at fixed angles. The hearth’s rotation is carried out with two induction motors (IM) supplied by inverters and the rotation is measured with incremental encoders. In this paper the calculus of the rotation step, taking into account the billet’s diameter, is carried out. Also the IM model is presented, the model in use is the fifth-order nonlinear model. Since the model is nonlinear the relay method is applied for the design of a PI motor speed’s controller. Using the designed controller the motor speed is simulated and the number of revolutions made ??by the motor is calculated. The starting and stopping of the furnace hearth by using acceleration and braking ramps is ensured via simulation.