Determination of harmonic power losses in non-oriented steel laminations for non-sinusoidal voltage waveforms

In this study, harmonic power losses occuring in non-oriented steel laminations for non-sinusoidal voltage waveforms are investigated. In the begining, after a short brief on electrical steel, eddy current and hysteresis loss equations which are commonly used in sinusoidal supply conditions are given. After that, as main objective, changes in histeresis and eddy current losses under non-sinusoidal supply voltage waveforms are obtained. Obtained histeresis loss expressions are also modified to cover additional minor loop losses. Unified iron loss expressions for non-sinusoidal voltage waveforms are given in terms of total harmonic distortion of magnetic field intensity. For easy interpretation, unified iron loss equations in terms of total harmonic distortion of suppy voltage are also given. For experimental proof of above aproach, a test circuit equipped with specially designed harmonic power supply and proper measuring and data acquisition devices are set to drive an EI type single-phase test transformer with non-oriented laminations. After having a series of saturation and frequency tests, a proper working point in magnetically linear region and loss parameters caracterising nonoriented electrical steel was obtained. The test transformer was subjected to nonsinusoidal supply voltage waveforms having different total harmonic distortion, and iron losses, current and flux changes was acquised. Comparative analysis of measured and calculated losses for non-sinusoidal voltage waveforms show that the error caused by the expressions obtained in this thesis stay less than 3% error while Steinmetz and Richter type classical loss calculation errors tend to %34, when the total harmonic distortion of the voltage tends to 100%.