The　in-depth　study　of　the　DC　voltage　balancing　for　the　delta　connection　cascaded　H　bridge　SVG　has　been　carried　out　in　this　paper.　A　three　layer　DC　voltage　balancing　control　system　is　proposed.　The　first　layer　is　the　total　DC　side　voltage　control.　Through　generating　fundamental　positive　sequence　active　current,　the　total　DC　side　voltage　of　all　three-phase　H　bridge　modules　is　maintained　constant.　The　second　layer　is　the　balancing　control　between　three　phases.　Through　injecting　zero　sequence　voltage　into　the　command　voltage　to　produce　zero　sequence　current,　the　three-phase　power　can　be　redistributed,　thus　the　DC　voltage　balancing　between　three　phases　is　achieved.　The　third　layer　is　the　balancing　control　between　each　module　in　each　phase.　Through　fine　tuning　of　the　command　voltage　of　each　module　in　each　phase　along　the　direction　of　the　current,　the　absorbed　power　of　each　module　can　be　redistributed,　thus　the　DC　side　voltage　of　each　module　in　each　phase　can　be　kept　as　the　reference　value.　Experimental　results　verify　the　correctness　and　reliability　of　the　proposed　control　method　in　the　end.　©,　2015,　Chinese　Machine　Press.　All　right　reserved.