hybrid modulation of a modular multilevel converter

摘要

A voltage source converter (to) comprises three phase legs, each having an upper and a lower arm (uua, vua, wua, ula, via, wla) with submodules (Su1, Su2, Su3, Su4, Sv1, Sv2, Sv3, Sv4, Sw1, Sw2, Sw3, Sw4), where the junction (ju, jv, jw) between the arms is connected to a corresponding AC terminal. There is also a control unit (CU) that operates one of the phase legs according to a first control scheme that is either a primary control scheme where the voltage at the junction (ju, jv, jw) resembles a section of a desired waveshape or a secondary control scheme where the voltage at the junction (ju, jv, jw) transitions between the two voltage levels with a slope and operates the two remaining phase legs according to a second control scheme that is the other of the primary and secondary control scheme.