There　is　an　inherent　correlation　between　the　carrier-based　PWM　and　SVPWM　in　two　level　inverters.　Some　researchers　have　proved　that　this　inherent　relationship　also　exists　between　those　two　modulation　strategies　in　three　level　inverters.　In　the　former　researches,　the　unity　correlation　was　focused　on　the　traditional　8　segments　SVPWM　switching　sequences,　but　it　couldn＇t　be　applied　to　some　switching　sequences　more　than　8　segments　obtained　by　using　redundancy　vectors　in　the　practical　SVPWM　modulation　strategy.　So　far,　seldom　researchers　have　the　unity　test　of　SVPWM　and　SPWM　under　these　conditions,　so　the　existing　unity　theory　between　SVPWM　and　SPWM　contains　some　shortage.　In　this　paper,　a　technique　of　decomposing　the　original　modulation　wave　into　two　sub-modulation　waves　has　been　proposed　which　is　utilized　to　discuss　the　unity　relations　between　SPWM　and　SVPWM　with　more　than　8　segments.　The　strict　theoretical　derivation　and　simulation　result　effectively　evolves　the　unity　theory　of　SPWM　and　SVPWM　successfully.　©　2013　Chin.　Soc.　for　Elec.　Eng.