Patent ID: 8923024

Claim:
A series-connected multi-level power conversion device comprising: a multi-winding transformer that distributes AC power input into a primary winding to m×n secondary windings, wherein n and m are coprime integers; and a power conversion unit that includes m×n single-phase power converters that are respectively connected to the m×n secondary windings, each of m output phases being constituted by serially connected outputs of n single-phase power converters of the m×n single-phase power converters, wherein the multi-winding transformer has a relationship that the m×n secondary windings have different voltage phases respectively, a second relationship that n secondary windings respectively connected to the n single-phase power converters in a same output phase have a voltage phase difference of 60/n degrees, and a third relationship that m phase-groups each having n voltage phases of the n secondary windings and respectively corresponding to the in output phases have a second voltage phase difference of 60/m degrees between the m phase-groups.