Algorithms of Optimal Funcioning Two-Section Induction Heater In Transient Modes

The transient modes play an important role at operations of the “heating - straining” process line. These include starting the process line after planned or emergency stops and changing the work pace of the hot straining equipment. An important task of the induction heating control during transient modes is the search for the optimal operation mode of the heating line, which ensures minimal total losses when the heater reaches a steady state. The present article solves the problem of minimizing energy consumption during the transition of a continuous two-section induction heater to a steady state mode. The design of optimal control algorithms in transient modes is based on the electrothermal model, taking into account the nonlinear relationship of the distribution of the specific heating power in each section with the temperature distribution along the radial and axial coordinates. It is shown that temperature deviations, which occur during the transient modes of continuous heaters can significantly exceeds the limits of technological tolerances. Under these conditions, the optimal control search problem is to determine the algorithms for changing the power of each section and the moment when the billet starts to move through the heater. The obtained algorithms provide the minimum balance delay of straining equipment and the minimum unproductive waste energy for heating substandard billets. The paper estimates the control algorithms effectiveness for the starting mode from the “cold” state and from the “thermostatic temperature control” mode. Some variants of energy efficient start-up control algorithms are proposed, which depend on the specific conditions of the technological process and requirements for process quality indicators.