Flying capacitor voltages estimation in three-cell converters using a discrete-time Kalman filter at one third switching period

Aims at reducing the number of sensors in multi-cell converters by estimating the capacitor voltages using a load current measurement. To achieve this purpose, the authors first present a simple discrete-time model which correctly represents the behavior of the converter in closed loop operation. A discrete Kalman filter (KF) is then detailed for the state estimation in a three-cell converter. Simulation results in the presence of measurement noises are presented to validate this observer. Thereafter, the influence of the sampling period and the process noise covariance matrix in the parametric robustness of the observer is examined.