Comparative Analysis of Methods for Calculating the Parameters of the Electrical Equivalent Circuit of Asynchronous Motors

Abstract

Experimental estimation of energy efficiency of power complexes with asynchronous motors is hardware-consuming and requires high qualified human resources. Mathematical modeling ensures a convenient assessment of energy performance of asynchronous electric drives. Mathematical modeling is relying on an adequate equivalent circuit of the asynchronous motor. The known methods of determining parameters for the equivalent circuit of asynchronous motors include those based on cataloged, reference and experimental data. This paper proposes the algorithm for determining parameters of the motor equivalent circuit founded on recording dynamical modes of the electric drive operation. The procedure provides the motor parameter identification according to oscyllographs of electric and electromechanic characteristics. Parameters are recorded in the modes of start, real and ideal idle run and coasting.  Analog signals of phase currents, voltages, motor shaft rotation rate are converted into digital ones to form a database. This database and the developed algorithm enable calculation of parameters for the equivalent circuit. With the latter, operational, power and mechanical characteristics of the asynchronous motor may be calculated by means of the known methods. The paper provides the analysis of different known methods for determination of parameter of the equivalent circuit of the asynchronous motor. The performed comparative analysis of known methods for calculation of equivalent circuit parameters and the method proposed has proved high accuracy of the latter that can substitute an experimental one identifying parameter by means of  the loading unit.  The study outcome may be used by specialists of the electric machine industry and those involved in energy audit of the electrical engineering complexes.