MODULATION FOR A 9-STEPS H-BRIDGE CASCADE CONVERTER WITH A VOLTAGE BALANCING ALGORITHM FOR THE DC LINKS

Abstract

This paper presents the development of a modulation algorithm that
integrates the voltage balancing algorithm on the capacitor for a 9-steps
converter connecting the H-bridge stage to the isolated DC side. In cascade
multilevels converters, if the voltage across the capacitors is not equalized, the
harmonic quality will decrease, and the current loop will not work properly.
Therefore, the requirement for the modulation algorithm is that when the DC
capacitors have a difference in value, the voltage between the capacitors must
still be close to the same value. The algorithm is built for a 9-levels single-phase
H-bridge cascade converter consisting of 4 bridges. The applicability of the
algorithm will be verified by simulation results on Malab/ Simulink.