Stacked multicell converter (SMC): reconstruction of flying capacitor voltages

We present in this paper a new method for the observation of the flying capacitor voltages dedicated to stacked multicell converters (SMC). Unlike the imbricated-cell converter, the new SMC topology allows increasing the input voltage level while decreasing the energy stored in the converter. This consists of a hybrid association of commutation cells, which enables to share the voltage constraint on several switches. During normal operation, the flying capacitor voltages have to be kept constant by the control strategy. Due to high voltage/high power applications, it is difficult and expensive to measure the flying capacitor voltages. Therefore, a new method has been developed to estimate those voltages. After an introduction and a brief reminder on the SMC topology, we will present a new strategy to estimate the capacitor voltages based on the determination of an image of those ones regarding the control signals and the chopped voltage. The influence of the measurement noise on our new technique has also been studied carefully and appropriate strategies have been developed. The last part will be devoted to conclusions and perspectives