Cascaded　H-bridge　(CHB)　inverters　used　in　high-voltage　variable　frequency　drives　are　usually　composed　of　several　power　cells.　Each　power　cell　consists　of　a　three-phase　uncontrolled　rectifier　as　its　input　stage　and　a　single-phase　inverter　as　its　output　stage.　It　is　difficult　to　obtain　the　analytical　expression　of　the　dc-link　capacitor　current　because　of　both　the　nonlinear　characteristics　of　the　uncontrolled　rectifier　and　the　low-frequency　harmonics　caused　by　the　single-phase　inverter.　On　the　other　hand,　exact　analysis　of　the　capacitor　current　is　important　for　dc-link　capacitor　selection.　This　paper　proposes　an　analytical　method　for　calculating　the　capacitor　current.　Considering　both　the　input　current　of　the　inverter　and　the　output　current　of　the　rectifier,　an　approximately　linear　equivalent　circuit　model　is　established.　According　to　the　proposed　equivalent　circuit　model,　the　analytical　expressions　of　the　harmonic　spectrum　and　the　root　mean　square　value　of　the　capacitor　current　are　derived.　The　capacitor　ripple　voltage　is　further　estimated.　Applicable　conditions　of　the　proposed　method　are　also　presented.　This　method　may　be　useful　when　designing　dc-link　capacitors　of　power　cells　in　CHB　inverters.　Simulation　and　experimental　results　show　that　the　proposed　method　can　achieve　good　accuracy　in　the　continuous　conduction　mode.