SETUP AND INVESTIGATION OF THE OPERATION MODES OF THE SPEED OBSERVER IN A CONTROLLED DC ELECTRIC DRIVE
Authors: Glazyrin Alexander S. , Kladiev Sergey N. , Timoshkin Vadim V. , Bolovin Evgeniy V. , Kozlova Lyudmila E. , Nabunskiy Ivan A. , Rakov Ivan V. , Popov Semen S. 
Published: July 2023

In modern closed-loop controlled electric drives used in manufacturing, the use of speed, current, torque, and other technological variable sensors is required. In some cases, indirect estimation of the electric drive state vector is required, when the use of technological parameter sensors (primarily speed sensors) is difficult or impossible. One of the problems is the length of the information cable in the feedback channel from the actuator to the power converter, which makes it difficult to use direct measurement methods. There are also difficulties in using sensors in an aggressive environment. For example, in the coal mining industry, electric motors or the entire electric drive are often located in an explosion-proof enclosure, and installing additional sensors will require expensive modernization of the entire system. State observers in sensorless electric drives allow restoring unmeasurable state vector components based on measured electrical signals in the power converters of the electric drive. From the perspective of a closed-loop controlled electric drive system, the main feedback is the feedback on the angular rotation frequency. Electric drives based on separately excited DC motors (SEDC) are simpler to investigate and implement such systems. The linearized mathematical model of an SEDC contains a relatively smaller number of differential equations compared to variable frequency drives due to the presence of independent channels for forming magnetic flux in the air gap and electromagnetic torque, which simplifies the analysis and synthesis of sensorless control systems using speed observers. Researching the observer of angular rotation for DC electric drives allows for developing design skills on a simpler system before moving on to variable frequency drives. Research in this area for both DC and AC electric drives is promising because it allows for an increased range of regulation and accuracy of the output coordinate in sensorless electric drives at the required level. This article is dedicated to the study of the properties of speed observers for DC electric drives with independent excitation of various structures. Aim of research Analysis of rotation frequency observer structure in DC motor drives with error reduction based on the proportional principle. Research methods Theoretical and experimental research methods were used in this study. Theoretical methods included the theory of automatic control, state observer theory, theory of electric drives, theory of electric machines, mathematical modeling, systems of differential equations, Laplace transforms, and numerical methods for solving differential equations. Experimental studies were conducted on a software-hardware complex, where the genetic algorithm method was used to identify the parameters of the electric machine equivalent circuit. Results Analytical expression for the characteristic equation roots for the investigated structure of the DC motor drive's speed observer was obtained. Based on this expression, stability criteria and trends in changes of the quality indicators for the angular velocity estimation were determined with varying observer coefficients.