This　article　presents　a　two-mode　controlled　step-up　inverter　(TMCSI),　which　is　capable　of　handling　single　or　dual　inputs　with　a　wide　range　of　dc　input　voltage.　In　comparison　to　traditional　multistage　dc/dc　power　conversion　systems,　the　power　conversion　stage　is　reduced　and　the　voltage/current　stress　of　device　is　significantly　alleviated　without　using　high-voltage　dc-bus　capacitors.　As　a　result,　the　reliability　and　overall　conversion　efficiency　are　improved　accordingly.　By　combining　the　two　working　modes,　the　proposed　inverter　achieves　uniform　distribution　of　duty　ratio　under　single/dual-input　with　a　wide　range　of　input　voltage,　and　thereby　is　very　suitable　for　systems　having　large　input　voltage　variation.　Moreover,　based　on　the　dual-input　TMCSI,　a　novel　power　allocation　method　is　also　proposed　to　improve　the　system　load-bearing　ability.　The　power　allocation　method　is　controlled　separately　from　two　working　modes　that　allows　the　two-input　sources　directly　supply　the　ac　load　simultaneously.　In　this　article,　topology　derivation,　two-mode　control　strategy,　characteristics　of　steady　principle,　and　design　criteria　for　the　key　circuit　parameters　are　systematically　analyzed,　and　important　conclusions　are　obtained.　Finally,　the　experimental　results　from　the　single/dual-input　500　VA　96-192　Vdc　input　and　220　Vac/50　Hz　output　inverter　prototype　verify　the　effectiveness　of　the　proposed　TMCSI　topology　and　its　associated　power　regulation　approach.　©　1986-2012　IEEE.