Dynamic properties of the torque-control system in an electric drive with a double-fed asynchronous machine

Abstract

Dynamic properties of an open-loop system of control of the electromagnetic moment that is part of an electric drive with a double-fed asynchronous machine have been considered. Analysis of a system of control of the electromagnetic moment with a subordinate system of control of currents of the stator and rotor windings of an asynchronous machine under the frequency control of the speed has been performed. Mathematical models of the elements comprising the system of the electromagnetic-moment control have been considered. These models describe the power part, the current controllers, and the regime former. In description of the elements of the electromagnetic-moment control system, the saturation of the main magnetic circuit of the machine has been taken into account. The program of the simulation of the processes is mainly aimed at the investigation of the effect of the speed of response of the current-control system on the dynamics of the open-loop system of the electromagnetic-moment control. Results of the simulation of the processes in the system of the electromagnetic-moment control at different speed of response of the current-control system are given. It has been shown that, with a decrease in the speed of response, the current controller begins losing the capability of compensating the effect of the disturbing action (the asynchronous machine speed is taken as this action). As a result, the orientation of the coordinate system, which is implemented by the moment controller, is disturbed and the dynamic characteristics of the systems of control of the electromagnetic moment and speed become worse. At a given speed of response of the current-control system, the characteristics of the efficiency of an open-loop system of control of the electromagnetic moment depend on the magnitude and speed of change in the controlling and disturbing actions. The dynamics of the system of the moment control is illustrated by graphs of transient processes in the case of a stepped setting of the controlling action and of the linear increase in the disturbing action. Based on the results of the investigations performed, the main conclusions and recommendations have been made.