Mathematical Model of a Solid Rotor Asyncronous Electric Machine

Abstract

The article deals with solid rotor asynchronous electric machine mathematical model. It is substantiated that the use of generalized electrical machine theory for building the mathematical model is rational at the design stage to analyze the electromagnetic and electromechanical processes in an electric machine and a power converter. The mathematical model with some circuits on the rotor was considered to account for the effect of current displacement in a solid rotor. We used the field theory to determine the number of circuits. For this purpose, the calculations series of the magnetic field distribution in the active part of the electric machine when the rotor is stationary (in short circuit mode) and the stator winding are powered by different frequencies currents were carried out. The modeling of a high-speed electric generator with a solid asynchronous rotor was carried out. Its power is 100kW and its rotational speed is 100 000 rpm. The analysis of the high-speed generator parameter approximation showed that the use of three circuits in the equivalent circuit is rational to account for the effect of current displacement in a solid rotor. The mathematical model results when connecting a rotating high-speed electric generator to a voltage source are showed. The assessment of the current displacement effect in a solid rotor was examined twice: with one circuit in a rotor chain and with three circuits in it. Comparison of the electromagnetic processes modeling results showed that the use of three circuits model provides the more accurate representation of electromagnetic processes in the solid rotor asynchronous electric machine. The modeling results significantly differs during transients when using the one-circuit model. In the steady state, the stator current fundamental harmonics and the average value of electromagnetic moment are the same for both models.