New Strategies for the Control of Electroheat Processes

Abstract

The increasing use of electroheat in complicated industrial processes makes it necessary to investigate the current electroheat control methods with a view to developing new strategies.
First, various models of electroheat processes are investigated. Methods for obtaining approximate models are evaluated in terms of their accuracy in the time domain.
An analytical investigation of on-off control systems is presented. Digital simulation techniques for on-off control systems are discussed, and computer programmes are given.
Open loop control of first and second order systems is investigated. The advantages and disadvantages of open-loop control are discussed. An indirect electroheat control scheme which uses a model of the plant in the feedback loop is proposed and discussed. It is shown that, by a suitable choice of the model parameters, performance criteria can be substantially improved.
Pulse-width modulation (PWM) control of electroheat processes is presented as an alternative to indirect control. An analysis of PWM control systems, with particular reference to electroheat processes, is given. Digital simulation programmes based on this analysis are also included. Stability conditions are investigated analytically and the results are verified both by digital and analogue simulation. An exact analysis of limit cycling in PWM electroheat control systems is presented. The results of this analysis are verified by using analogue and digital simulation. The potential advantages of PWM for electroheat control are discussed.

Date of Award	1970
Original language	English
Awarding Institution	Aston University