Reduction of Eddy Current Loss in Rectangular Coils Using Magnetic Shield: Analysis With Homogenization Method

Rectangular coils have been widely used in rotating machines and transformers because of high space factor and low dc resistance. However, eddy current losses due to skin and proximity effects in the rectangular coils cannot be ignored, especially when carrier harmonic increases. The eddy current loss due to the proximity effect would be effectively reduced by shielding the coils with a magnetic thin layer. In this paper, a method for homogenization-based analysis of a magnetically shielded rectangular coil is proposed. It is shown by the proposed method that the ac-resistance of a motor winding can be effectively reduced by introducing the magnetic shield.