Patent ID: 10491139

Abstract:
A modular converter assembly has at least one AC voltage terminal and at least two DC voltage terminals. The DC voltage terminals are formed by the outer terminals of a series circuit and the AC voltage terminal is formed by the connecting node between two sub-circuits of the series circuit. Capacitors of submodules of the subcircuits are activated or deactivated based on their capacitor voltages. The capacitors are operated exclusively in a unipolar mode or exclusively in a bipolar mode. In a time period in which the temporal mean value of the current flowing through the sub-circuit has a different sign than the actual current flowing through the sub-circuit, capacitors operating in a unipolar mode are preferred over capacitors operating in a bipolar manner. That is, the unipolar capacitors are reactivated or remain activated. A selection loop is carried out repeatedly to select the capacitors for activation or deactivation.