On observability and High Order Sliding Mode and adaptive observers design for a multicell chopper

In this paper, a hybrid model of a p cellular converter is developed. This hybrid model incorporates both the continuous and discrete states of the converter allowing better understanding of the operating modes of the system and its observability properties. Then, different strategies based on adaptive observer and HOSM (high order sliding mode) observer are proposed to estimate the (p-1) flying voltages of the converter. Finally, experimental results are presented in order to illustrate the performance and the drawbacks of each proposed approach.