Identification of Quasi-Global Extrema in the Calculation of Induction Motor Double-Loop Equivalent Circuit Parameters Using Numerical Methods

Boundary effects of the method for calculating the parameters of a double-loop equivalent circuit (EQC) of a deep-bar induction motor with a squirrel-cage rotor, based on the numerical solution of a system of nonlinear algebraic equations and underlying its synthesis in MathWorks® MATLAB® software package, are considered. The case of calculating the EQC of a high-voltage induction motor with a quasi-global residuals minimum with an unacceptably large rotor circuits time constants ratio of 2836 as well as stator current locus that does not correspond to the principles of constructing induction machines is considered. A comparison of the equivalent circuit synthesized using numerical and analytical methods via calculation of the induction motor direct start-up using differential equations was carried out. Recommendations for identifying inadequate EQCs with the help of stator current loci and replacing them with parameters obtained analytically are given.