Input-independent　and　output-series　dc-dc　converters　are　able　to　collect　photovoltaic　(PV)　energy　into　a　medium　voltage　dc　(MVDC)　grid　without　the　aid　of　a　low　voltage　dc　(LVDC)　bus,　thus　reducing　primary　power　losses　and　hardware　costs.　However,　in　this　series　structure,　a　short-circuit　fault　at　some　of　the　LV　ports　can　cause　the　whole　system　to　fail,　and　a　short-circuit　fault　at　the　MV　port　can　easily　damage　the　equipment.　In　this　article,　we　propose　a　new　fault-tolerant　structure　that　can　effectively　solve　the　above　problems.　During　an　LV　fault,　the　LC　branch　connected　between　adjacent　submodules　(SMs)　can　transfer　energy　and　support　the　capacitive　voltage　of　the　faulty　module　to　ensure　that　the　system　continues　to　operate　stably.　In　the　case　of　an　MV　fault,　the　fault-tolerant　structure　is　blocked　and　the　SM　capacitors　is　reversed　into　the　fault　circuit,　thus　reducing　the　fault　current　quickly.　The　proposed　structure　and　operating　principle　are　verified　through　experiments.