Z(TN)-Observability and control of parallel multicell chopper using Petri nets

This study deals with observability problems and control of the parallel multicell chopper. In the area of strong currents with high switching frequencies, new structures based on the combination of components have been developed. Among them, the authors find the parallel multicell converters that the authors studied in this study. This type of choppers is a DC/DC static power converter which has an output current equals to n (n is the number of cells) times the source current. After recalling the dynamical equations of the converter, its hybrid dynamical behaviour and properties are highlighted. This particular hybrid system induces new and difficult observability problems, such problem can be tackled by a new observability concept [the Z(TN)-observability]. However, for a large number of switching cells in parallel, the complexity of the system makes it impossible to predict the transient behaviour of the converter and therefore all predimensioning. The main disadvantage of this type of converter is the imbalance branches of current with increasing number of cells. Therefore modelling and control with Petri net is proposed to solve the problems of imbalanced of currents and the voltage output regulation with variation of the load. The authors approaches are attested by several numerical simulations considering noisy measurements and load variations.