In　order　to　evaluate　and　predict　the　core　losses　of　magnetics　in　power　converters,　by　equivalently　replacing　the　dynamic　B-H　loop　which　surrounding　area　reflects　the　core　losses　in　a　magnetizing　cycle　period　with　an　elliptical　loop,　the　model　of　magnetics　core　losses　under　the　PWM　excitation　without　DC　bias　was　derived.　The　core　losses　of　magnetics　under　both　DC　bias　and　PWM　excitations　using　a　DC/AC　inverter　as　the　test　circuit　were　measured　by　differential　loss　test　idea.　By　the　analysis　of　the　core　loss　test　results　and　their　characteristics,　a　new　core　loss　model　considering　the　effects　of　both　DC　bias　and　PWM　excitations　was　conceived　based　on　the　basic　B-H　curve.　Finally,　the　test　results　were　compared　with　the　proposed　model　and　the　model　accuracy　was　verified.　©2015　Chin.　Soc.　for　Elec.　Eng.