ANALYTICAL DESIGN OF A QUASIOPTIMAL REGULATOR FOR THE ELECTRIC FEED DRIVE OF STRAW CHOPPER

Abstract

The use of control systems for feed drives of straw chopper using of frequency inverters allows to ensure the stability of the load of the main motor of system, to ensure high-quality grinding of components. At the same time, a feature of the control system is the significant asymmetry of regulator output characteristic, which significantly complicates the synthesis procedure of the control law, accordingly. Existing regulators often do not provide the ability to adjust the load in a wide range and require reconfiguration when the operating parameters of straw are changed. An urgent task is the realization of the synthesis procedure of the control law, which provides a close to optimal behavior of load stabilization of the straw chopper main electric drive. The aim of the work is to solve the problem of analytical design of a quasioptimal feed regulator in the presence of significant asymmetric nonlinearity of control output. The method of dynamic programming for linearized systems and quadratic quality functional to solve the problem of synthesis of the feed regulator was used. To linearize significant nonlinearity, the "instant linearization" method was used. Using this method the nonlinear characreristic was replaced by a linear one, where the linearization coefficient is a control function. The transition from a linear control function to an adaptive one using the Pearson method was carried out. Using concept of Pearson's method allowed replacing the original non-linear problem of synthesis with a linear one, which is solved in each calculation cycle of the programmable logic controller. Using of modified minimization quality functional proposed by O.A. Krasovsky, made it possible to significantly simplify the procedure for finding the coefficients of the optimal regulator. Investigation the dynamic characteristics with proposed control system by the method of digital modeling was made. Comparison of the transients performance of the synthesized regulator with a linear one was made, and the advantages of the proposed approach were determined. The prospects for the further development of optimal control systems are formulated and the features of the practical implementation of the control algorithm are defined. Thus, the use of a synthesized regulator made it possible to improve the quality of drive load control; the proposed approach can be used for electromechanical systems in which the drive load by programmable logic controllers is controlled.