Determination of Equivalent Circuit Parameters of a Solid Rotor Asynchronous Electric Machine

The article deal with the determining the equivalent circuit parameters of a solid rotor asynchronous electric machine. To solve the problem, we determined the structure and parameters of a mathematical model using known geometric relationships and parameters of used materials. The least square method is used to determine the equivalent circuit parameters of an unlaminated-rotor asynchronous electric machine. The magnetic field distribution is calculated when the stator winding is supplying with a sinusoidal current and under short-circuit conditions. The imaginary part of the stator phase inductance versus stator current frequency when the rotor is fixed is calculated using the field theory. This dependence is approximated. The system of algebraic equations determining the approximation parameters is non-linear. The Levenberg-Marquardt method provides solution convergence of the equation system when using two or more loops on the rotor. The selection of the initial approximation largely determines the convergence of the solution made by the iterative method. The preliminary studies showed that the use of simplified scheme of the substitution of an asynchronous electric machine with one contour on the rotor is suitable as an initial approximation of parameters. The numerical solution of the equations determined the approximation parameters. The equivalent circuit parameters of high-speed electric generator with solid asynchronous rotor was made as an example of using of the approach under consideration. We need to use three loops on the rotor in the mathematical model of the asynchronous electric machine to take into account the effect of current displacement in solid rotor.