Power Distribution in Hybrid Multi-cell Converter with Nearest Level Modulation

Hybrid multi-cell converters present a highly nonlinear power distribution at each cell. Moreover, the cells with smaller DC link voltage can regenerate power, even if the load is not active. This paper shows the active power distribution in terms of the modulation index, highlighting the regenerative operation. The active power is calculated based on the fundamental term of the switching pattern obtained by the nearest level or round modulation. The round modulation technique is described as a comparison algorithm to allow a mathematical analysis. This paper shows that low power cells present a regenerative operation which depends on the modulation technique and does not depend of the load type. The modulation index rates of regenerative operation are found, as example, for a three-cell hybrid multi- cell converter for two different asymmetries.