Control method and device of modular multilevel converter

The invention discloses a control method and device for a modular multilevel converter, and belongs to the technical field of power electronics, and the method comprises the steps: marking all sub-modules on a bridge arm in sequence; measuring capacitance voltage and bridge arm current of each sub-module; after being triggered by a synchronizing signal, converting all capacitor voltages into square wave signals with variable pulse width, wherein the pulse width of the square wave signal is directly proportional or inversely proportional to the capacitor voltage; recording the labels of the sub-modules according to the arrival time sequence of the rising edge or the falling edge of the square wave signal to obtain a label sequence Qseq; and distributing driving signals in a pre-generated driving signal queue Qd to each sub-module according to the Qseq based on the direction of the bridge arm current so as to obtain bridge arm driving signals, thereby realizing voltage-sharing control. According to the inventio