Analysis and Proposal of Capacitor Voltage Control for an Asymmetric Cascaded Inverter

This work presents an analysis of the distribution of power handled by H-bridge cells of asymmetric cascaded multilevel converter. Applications of such converters require DC sources connected to DC link in order to establish constant voltage. The voltage must be independent of the modulation index and the load current. Even in applications like for SVAR compensation, where the inverter does not need to provide active power, the DC voltage must be present. The proposed control algorithm eliminates the need of additional isolated DC sources. The control strategy regulates the DC link voltages of capacitors connected to the two smallest voltages of a tree cells cascaded H-bridge inverter. Experimental results validate the voltage control strategy