Analysis And Calculation Of Coreless Transformer And Inductor In Printed Circuit Board

This article proposes to research the structural and electrical characters of coreless transformer and planar inductor in printed circuit board, to analyse their applicable prospect, to improve and perfect their performance, to extend their applicable field, and to realize the miniaturization of the transformer and inductor.This article expatiated on the structure and principle of coreless transformer in printed circuit board, introduced and analysed the Hurly_duffy's method to calculate the self and mutual inductance of coreless transformer in printed circuit board in which I found the fault, re-modified the current unit model, deduced a new formula used commonly, and offered testing process and circuit as well as mended the structure of coreless transformer which made the analysis easy.This article also provided two new types inductor in printed circuit board-bracelet and column inductor as well as deduced formula to calculate the inductance of loose column winding inductor. As the manufacturing technique develops constantly, the volume of bracelet and column inductor can be made smaller because of being sandwiched in the printed circuit board. When the distance between coils is short enough, bracelet winding can be considered the ideal tight winding and can not produce electro-magnetic interference because its magnetic flux concentrate the inside and the magnetic induction is zero outside. In multilayer printed circuit board the integration can be improved by sandwiching the bracelet winding, coreless transformer-bracelet transformer evolved from bracelet winding has small flux leakage near to full coupling transformer as well as has higher transforming efficiency.The coupling coefficient of transformer relates the transforming efficiency. This article has analysed the factor that determined the coupling coefficient and has drawn a conclusion which would play a positive role to instruct next research.