The influence of rotating field direction on core losses in electrical machine laminations

Abstract

The measurements of rotational core loss in machine laminations show significant differences in losses when the rotating field reverses its direction from clockwise (CW) to counterclockwise (CCW) direction of excitation. A novel design of a magnetizing test fixture based on an electromagnetic Halbach array is used to perform measurements on a non oriented silicon steel sample of M36G29 at three different frequencies of interest to the industry 60 Hz, 400 Hz, and 1 kHz. The experimental results are fed to three types of electrical machine models, 2-pole induction machine (IM), 6-4 switched reluctance motor (SRM), and 2-pole brushless DC machine (BLDC) to investigate the effect of reversal of the rotating field direction on the delivered core loss in the stator. Results reveal that the IM experiences the highest effect of field reversing followed by the BLDCM, and then the SRM which is the least affected.