An interconnected adaptive observer for flying capacitor multilevel converters

A nonlinear adaptive observer for flying capacitor converters is proposed. The observer estimates simultaneously the capacitor voltages and the load resistance, which adds robustness and improves estimation when system parameters are uncertain. Proposed scheme takes advantage of the converter structure to represent the system as a set of n interconnected subsystems, which allows to overcome the unobservable condition of the original system.This observer can be used to replace the voltage sensors needed to control and monitoring the capacitor voltages. Experimental data is used to validate and evaluate the performance of the proposed scheme.

► Capacitor voltage in flying capacitor multilevel is estimated by a nonlinear observer.
► Observer is designed taking advantage of the cascaded model structure.
► Observer is validated from experimental data.
► An adaptive parameter estimation is incorporated in order to enhance state estimation.
► Estimation is sufficiently accurate for monitoring and control purposes.
► Observer could increase reliability by reducing hardware complexity.