Journal of Magnetism and Magnetic Materials 112 (1992) 457-459 North-Holland Field computation of three phase three limb and three phase five limb transformer cores constructed from amorphous material G.H. Shirkoohi and Jin Liu Wolfson Centre for Magnetics Technology, School of Electrical, Electronic and Systems Engineer#,g, Unil'ersity of Wales Cardiff, Wales, UK Finite element analysis of three phase three-limb, and five-limb stacked core amorphous transformers are presented, and compared with those of model cores constructed from amorphous material and grain-oriented steel. The results show that finite element analysis is ideally suited to solve devices constructed from almost isotropic amorphous materials. 1. Introduction 2. Finite element analys}s Recent developments in the production of amorphous materials have made them better suited for the construction of stacked core trans- formers. Apart from the almost ideal isotropic properties, they also exhibit very low specific iron loss, together with lower magnetostriction due to the increased silicon content. For many years the thin gauge and the difficulty in handling the materials had proved to be a detriment for their utilisation in electromechanical devices. New pro- duction methods have resulted in better more workable materials such as Powercore *. The isotropic properties of materials such as Power- core, indicates that electromagnetic devices con- structed from these materials can be analysed using finite element techniques with relative ease. Computation of magnetic field and flux density for two experimental transformer core models were obtained using a PE2D finite element pack- age, for comparison with experimental results. Correspondence to: Dr. G.H. Shirkoohi, Wolfson Centre For Magnetics Technology, 30 The Parade, Roath, Cardiff DF2 3AD, UK. * Powercore is a registered trademark for amorphous consol- idated strip material of Allied-Signal inc. Two three phase transformer core geometries were investigated, a three-limb core of dimension 500 × 500 cm 2 and equa~ limb and yoke widths of 10 cm, and a five-limb core of similar overall magnetic path, with approximately half the height of the three-limb geometry. Instantaneous magnetos'tatic solutions for each design geometry was obtained over half of the magnetisation cycle between 0 ° and 180 °, in time steps of 18° for an equivalent core magnetisation of 1.3 T, 50 Hz. The solutions were then com- bined together to evaluate the localised rotational components of flux density in various regions of the cores. 3. Results and discussiov Fig. 1 shows the distribution of the localised rotational fundamental component of flux in the three limb core energised at 1.3 T. The figure shows that fundamental flux is mostly alternating within the centre of the limbs and corner regions of the transformer core geometry. A unifor=, spread of rotational flux is also observed in ne T-joint as expected. The results are similar to those previously reported for experimentu: amor- phous cores by Moghadam and Moses in Power- 0304-8853/92/$05.00 © 1992 - Elsevier Science Publishers B.V. All rights reserved