METHOD FOR OPERATING A MULTI-PHASE MULTI-STAGE POWER CONVERTER AND A CORRESPONDING MULTI-PHASE MULTI-STAGE POWER CONVERTER

The invention relates to a multi-phase multi-stage power converter (MMC) and a method for the operation thereof, wherein the multi-stage power converter (MMC) comprises a plurality of phase modules (210) which are each formed from sub-modules (610) with an energy store (724), and wherein a main control voltage (UStell) is output as a function of a specified setpoint current (IS). In order to achieve clearly reduced circuit feedback with relatively few sub-modules (610) per phase module (210), it is proposed that each phase module (210) is formed from a plurality of groups (G1, G2) of sub-modules (610) series-connected directly one after the other, that the DC link voltages (Uzk) of the energy stores (724) of the sub-modules (610) of each group are the same and the DC link voltages (Uzk) of different groups of a phase module (210) are different, that each group (G1, G2) is allocated a weighting factor (WF1, WF2) the sum of which equals one, that partial control voltages (UST1, UST2) are allocated by way of the weighting factor for the group (G1, G2), that the sub-modules (610) of the group (G1, G2) are each controlled dependent on the partial control voltage (UST1, UST2), that the energy stored in the energy stores (724) of the sub-modules (610) is calculated, and the total energy (Wi) is compared with an energy setpoint value (Wsoll) to determine a correction current (Iladen) by which the specified setpoint current (IS) is corrected in each case.