There　are　a　lot　of　inductor　working　at　unipolarity　status　all　the　time　in　the　power　conversion.　The　magnetization　B-H　curve　in　the　first　quadrant　all　the　time.　The　pre-bias　technology　based　on　the　permanent　magnet　(PM)　could　move　the　start　point　of　B-H　curve　from　zero　point　to　the　opposite　direction.　Thus　it　could　broaden　the　working　range　of　B　value,　and　is　better　for　reducing　choke　volume.　Conventional　pre-bias　inductor　put　the　PM　in　the　magnetic　core　air　gap　or　in　the　outside　in　parallel.　But　this　solution　would　cause　serious　eddy　current　loss　when　the　high　frequency　magnetic　flux　passed　through　the　PM,　and　the　choke　loss　would　increase　significantly,　thus　the　higher　temperature　would　cause　demagnetization　risk　for　PM.　This　paper　introduced　a　magnetic　loop　design,　it　could　solve　these　problems　based　on　this　built-in　type　PM　for　pre-bias　technology.　Based　on　the　theoretical　analysis　and　electromagnetic　field　simulation　and　experimental　verification,　the　result　shows　this　solution　could　effective　solve　application　problems　in　high　frequency　pre-bias　inductor.　©　2019,　Electrical　Technology　Press　Co.　Ltd.　All　right　reserved.