STUDY OF SLIDING MODE CONTROL SYSTEM, SYNTHESIZED BY THE N-i SWITCHING METHOD, FOR ELECTRIC SERVO DRIVE WITH INERTIAL POWER CONVERTER

Abstract

Electric drives are characterized by the restriction of intermediate coordinates in transient modes. Such restrictions are implemented by a system with cascade controllers. The N-i switching method, which has a relatively simple mathematical apparatus, provides optimization for the speed of cascade sliding mode control systems. In this paper, a comparative study of the typical dynamic modes of such systems with idealized and real control objects is performed. In this case, a cascade of integrators was considered as an idealized control object, and an electric drive with a power section constructed according to the thyristor converter - a DC motor was used as a real one. The speed optimization of both systems is based on the calculated trajectories of the idealized control object. The study of the servo drive control system revealed a slight deviation of the transition trajectory from the calculated one. The cause of this effect is the influence of the internal feedbacks of the electromechanical system, leading to the premature entry of regulators into the sliding mode. The same circumstance contributes to a significant reduction in the duration of shock perturbations compensation by real system compared to the ideal one. The results obtained in the work are supported by specific numerical examples. Due to the simplicity of the computational procedures, the N-i switching method provides real-time adaptation of the control system settings to the shape of the optimal transient trajectory. The results of the research open the prospect on practical realization of adaptive algorithms for the synthesis of cascade sliding mode control systems based on the N-i switching method.