Iron losses in AC machines due to rotational flux conditions

Core losses in rotating AC machines are largely caused by flux which rotates in the plane of the machine laminations. Reduction of rotational losses in motor cores could greatly lower AC machine operating costs. This paper discusses rotational losses and how they are produced in AC machines. Steel producers would like a standardized test for rotational losses in order to investigate the effects of composition and processing variables. This is necessary in order to produce low loss steels for motor applications. Motor manufacturers would like rotational loss data as a material characteristic in the same fashion that Epstein test results are provided for alternating losses. The development of analysis tools for determining the amount of rotational flux and degree of polarization in a machine core is also imperative. The authors have investigated a time harmonic finite element formulation utilizing Magnet 2D, a commercially available package