This　paper　analysed　the　current　waveforms　in　the　measuring　resistance　concatenated　with　the　direct　current　bus　in　the　general　converter.　The　relation　between　the　resistance　current　and　the　load　current　was　investigated.　The　system　is　simplified　by　seeking　the　signal　processing　circuit,　which　makes　the　resistance　measure　the　load　current　and　realize　the　protection　in　overload,　overcurrent　and　short-circuit.　The　current　waveforms　in　the　practical　application　were　presented.