Saturated induction machine steady-state performance assessment through simulations

This paper presents results regarding the influence of the magnetic core saturation on the steady state performances of the induction machine (IM). The assessment is done through simulations performed with an IM model developed with the use of state equations and modified nodal equations. When analyzing the induction motor operating at steady state, we´ve considered a modified version of the well-known Π (Steinmetz) per-phase equivalent circuit. In the modified circuit, the magnetizing inductance is considered as a current-controlled nonlinear inductor, while the rotor resistor as a time-variable resistor. For simulations we used two software packages: ENCAP (Electrical Nonlinear Circuit Analysis, which is based upon modified nodal equations) and SYSEG (Symbolic State Equation Generation, which is based upon state equations). The state equations can be integrated through an existing routine from MATLAB/Simulink package. The features of the above mentioned programs include the Fourier analysis capabilities, with the direct application to calculating the harmonics of every order present in the current and voltage waveforms. Following the computing of harmonic content, we assessed the steady state characteristics (power factor, efficiency, etc) of the induction motor.