Improved Equivalent Circuit of Induction Motor considering Iron-loss Calculated by Novel Analysis Method for Flux Density Harmonics

Abstract

Using time-harmonic analysis, a method to identify load-dependent parameters of the induction motor (IM) equivalent circuit considering iron-loss is presented. Time-harmonic analysis is generally used for IM analysis due to its fast speed. However, iron-loss caused by harmonics cannot be calculated, since it regards that all parameters are sinusoidal. Thus, time-transient analysis is used to consider harmonics in general. A complete period of rotor flux density is needed for iron-loss calculation, and is inversely proportional to slip. Since IM is operated under very low slip condition, it takes immoderate time. Accordingly, novel analysis method for flux density harmonics for calculation of iron-loss. Based on the nature that result of time-harmonic analysis is in the form of complex number, method, which enables harmonics analysis with very short analysis range, is presented. Finally, the impact of considering iron-loss to equivalent circuit is investigated to demonstrate the accuracy improvement.