Consideration of Design and Operation on Rotational Flux Density Distributions in Hydrogenerator Stators

Core losses in an electrical machine vary depending on the type of material, frequency of operation, and flux density magnitude and waveform. Loss prediction using pulsating models is insufficient for estimating core losses in a machine, since it does not take into account rotational core losses. Moreover, superposition of pulsating losses in the radial and tangential direction overestimates losses especially at higher flux densities. The objective of this paper is to study rotational flux distribution in the stator of the generator under different operating conditions. Distribution of rotational flux in a large hydrogenerator stator is studied by plotting the aspect ratio. It was found that increasing the yoke length and reducing the air gap increases the area of the stator with rotational flux. Varying the output power showed slight changes in the rotational flux distribution. Different optimized machine designs are investigated for rotational flux distribution; moreover, rotational core losses are measured and used for a comparative study radially across the stator.