To adjustment of pulsed-width modulators in relay-pulsed systems of automatic control of metallurgical furnaces

Introduction. In automation systems for metallurgical furnaces, relay-pulse controllers are widely used, which contain actuators (IM) of constant speed. In this paper, we consider the problem of formalizing the procedure for setting up a pulse-width modulator (PWM) operating as part of such a controller. The PWM structure contains an adder, an integrator and a three-position relay element (RE), which has return zones in the left and right parts of its characteristic. Purpose of the study. Set the dependences of the duty cycle and the pulse repetition period on the characteristics of the PWM structural elements. Optimization of the PWM setting contributes both to improving the quality of transients in automatic control systems and to improving their mode of operation, which ultimately leads to an increase in the efficiency of furnaces. Materials and methods. A review of the literature data on the problem under consideration is carried out. A physico-mathematical analysis of the processes occurring in the specified PWM structure has been carried out. Results. Dependencies are established that describe the PWM operation mode on the parameters of the elements contained in it. In particular, it is shown that with an increase in the return zone, as well as the integration time constant of the integrator, the pulse repetition period unambiguously increases, and as a result, it is clear that the switching frequency of the actuator decreases. At the same time, with an increase in the level of the output signal of the RE, the period decreases, and the frequency of switching on the actuator, on the contrary, increases. The attractive rationality of the approach used in regulating microprocessor controllers of the REMIKONT type to the problem of pulse-width modulation is shown. Conclusion. The obtained relations can be used to algorithmize the procedure for setting the considered type of PWM, which contributes to both improving the quality of regulation of the technological parameters of metallurgical furnaces and reducing the wear of the actuator and its start-control equipment.