PRACTICAL ASPECTS OF IMPLEMENTATING THE AUTOMATIC CONTROL SYSTEMS CORRECTORS

Abstract

Besides the direct influence channels of input values on output values, muffle furnaces with two independent power sources have cross channels of influence, which significantly complicates the automatic control of the furnace's thermal regime. One of the methods of cross effects compensation is the introduction of a cross connections compensator into the control circuit; the dynamic properties of the compensator are determined by the transfer functions of the furnace muffles (control object). The dynamic properties of the control object are described by four transfer functions of the same structure, each of which has the third order, and, therefore, the transfer functions of the compensator will have the 16th order. Such a high order of transfer functions significantly complicates their practical implementation on modern microprocessors (controllers). Due to this, the objective emerged to simplify the transfer functions of the compensator without significantly losing the efficiency of its functioning.

The reduction of the mathematical models of the compensator was carried out by evaluating the influence of the poles on the time characteristics, which made it possible to reject insignificant ones and transfer the reduced model to a discrete domain. This method of reduction belongs to modal methods that preserve the significant poles of the original control system.

The resulting recursive programmable representations of the digital cross-link compensator are implemented in a direct, sequential, or parallel structure scheme using math and delay blocks that are available in the algorithm libraries of many PLCs.