Voltage-Balancing Control in Stacked Multicell Converter Based on Single Space-Vector Modulation

This article introduces voltage-balancing control methods in stacked multicell converters based on single space-vector modulation. Two different control strategies for capacitors voltage are presented. The basic vectors with the smallest common-mode voltage are chosen to accomplish the voltage-balancing control. The nearest vector is selected for the first proposed method, and the appropriate switch combinations of each phase are determined by the cost function of floating-capacitor voltages and neutral point (NP) voltage. For the second proposed method, we consider sacrificing a little current performance to provide more possibility of switching state selection. The switching state of each phase is determined according to the voltage-balancing control of floating capacitors, and the optimal switching state with the smallest NP voltage is selected from the two nearest adjacent basic vectors. Experimental results compared with the existing space vector pulsewidth modulation method are presented to verify the effectiveness of the proposed methods.